How to convert the below synchronous ajax call to asynchronous?

Hi Sampath,

Please find below the code which you has asked:

01) :: jquery.ValidationEngine.js :: (check lines 472 and 519)

/*
* Inline Form Validation Engine 2.2, jQuery plugin
*
* Copyright(c) 2010, Cedric Dugas
* http://www.position-absolute.com
*
* 2.0 Rewrite by Olivier Refalo
* http://www.crionics.com
*
* Form validation engine allowing custom regex rules to be added.
* Licensed under the MIT License
*/
(function ($) {

    var methods = {

        /**
        * Kind of the constructor, called before any action
        * @param {Map} user options
        */
        init: function (options) {
            var form = this;
            if (!form.data('jqv') || form.data('jqv') == null) {
                methods._saveOptions(form, options);

                // bind all formError elements to close on click
                $(".formError").live("click", function () {
                    $(this).fadeOut(150, function () {

                        // remove prompt once invisible
                        $(this).remove();
                    });
                });
            }
        },
        /**
        * Attachs jQuery.validationEngine to form.submit and field.blur events
        * Takes an optional params: a list of options
        * ie. jQuery("#formID1").validationEngine('attach', {promptPosition : "centerRight"});
        */
        attach: function (userOptions) {
            var form = this;
            var options;

            if (userOptions)
                options = methods._saveOptions(form, userOptions);
            else
                options = form.data('jqv');

            var validateAttribute = (form.find("[data-validation-engine*=validate]")) ? "data-validation-engine" : "class";

            if (!options.binded) {
                if (options.bindMethod == "bind") {

                    // bind fields
                    form.find("[class*=validate]:not([type=checkbox])").bind(options.validationEventTrigger, methods._onFieldEvent);
                    form.find("[class*=validate][type=checkbox]").bind("click", methods._onFieldEvent);

                    // bind form.submit
                    form.bind("submit", methods._onSubmitEvent);
                } else if (options.bindMethod == "live") {
                    // bind fields with LIVE (for persistant state)
                    form.find("[class*=validate]:not([type=checkbox])").live(options.validationEventTrigger, methods._onFieldEvent);
                    form.find("[class*=validate][type=checkbox]").live("click", methods._onFieldEvent);

                    // bind form.submit
                    form.live("submit", methods._onSubmitEvent);
                }

                options.binded = true;
            }

        },
        /**
        * Unregisters any bindings that may point to jQuery.validaitonEngine
        */
        detach: function () {
            var form = this;
            var options = form.data('jqv');
            if (options.binded) {

                // unbind fields
                form.find("[class*=validate]").not("[type=checkbox]").unbind(options.validationEventTrigger, methods._onFieldEvent);
                form.find("[class*=validate][type=checkbox]").unbind("click", methods._onFieldEvent);
                // unbind form.submit
                form.unbind("submit", methods.onAjaxFormComplete);


                // unbind live fields (kill)
                form.find("[class*=validate]").not("[type=checkbox]").die(options.validationEventTrigger, methods._onFieldEvent);
                form.find("[class*=validate][type=checkbox]").die("click", methods._onFieldEvent);
                // unbind form.submit
                form.die("submit", methods.onAjaxFormComplete);

                form.removeData('jqv');
            }
        },
        /**
        * Validates the form fields, shows prompts accordingly.
        * Note: There is no ajax form validation with this method, only field ajax validation are evaluated
        *
        * @return true if the form validates, false if it fails
        */
        validate: function () {
            return methods._validateFields(this);
        },
        /**
        * Validates one field, shows prompt accordingly.
        * Note: There is no ajax form validation with this method, only field ajax validation are evaluated
        *
        * @return true if the form validates, false if it fails
        */
        validateField: function (el) {
            var options = $(this).data('jqv');
            return methods._validateField($(el), options);
        },
        /**
        * Validates the form fields, shows prompts accordingly.
        * Note: this methods performs fields and form ajax validations(if setup)
        *
        * @return true if the form validates, false if it fails, undefined if ajax is used for form validation
        */
        validateform: function () {
            return methods._onSubmitEvent.call(this);
        },
        /**
        * Displays a prompt on a element.
        * Note that the element needs an id!
        *
        * @param {String} promptText html text to display type
        * @param {String} type the type of bubble: 'pass' (green), 'load' (black) anything else (red)
        * @param {String} possible values topLeft, topRight, bottomLeft, centerRight, bottomRight
        */
        showPrompt: function (promptText, type, promptPosition, showArrow) {

            var form = this.closest('form');
            var options = form.data('jqv');
            // No option, take default one
            if (!options) options = methods._saveOptions(this, options);
            if (promptPosition)
                options.promptPosition = promptPosition;
            options.showArrow = showArrow == true;

            methods._showPrompt(this, promptText, type, false, options);
        },
        /**
        * Closes all error prompts on the page
        */
        hidePrompt: function () {
            var promptClass = "." + methods._getClassName($(this).attr("id")) + "formError";
            $(promptClass).fadeTo("fast", 0.3, function () {
                $(this).remove();
            });
        },
        /**
        * Closes form error prompts, CAN be invidual
        */
        hide: function () {
            var closingtag;
            if ($(this).is("form")) {
                closingtag = "parentForm" + $(this).attr('id');
            } else {
                closingtag = $(this).attr('id') + "formError";
            }
            $('.' + closingtag).fadeTo("fast", 0.3, function () {
                $(this).remove();
            });
        },
        /**
        * Closes all error prompts on the page
        */
        hideAll: function () {
            $('.formError').fadeTo("fast", 0.3, function () {
                $(this).remove();
            });
        },
        /**
        * Typically called when user exists a field using tab or a mouse click, triggers a field
        * validation
        */
        _onFieldEvent: function () {
            var field = $(this);
            var form = field.closest('form');
            var options = form.data('jqv');
            // validate the current field
            methods._validateField(field, options);
        },
        /**
        * Called when the form is submited, shows prompts accordingly
        *
        * @param {jqObject}
        *            form
        * @return false if form submission needs to be cancelled
        */
        _onSubmitEvent: function () {
            var form = $(this);
            var options = form.data('jqv');

            // validate each field (- skip field ajax validation, no necessary since we will perform an ajax form validation)
            var r = methods._validateFields(form, true);

            if (r && options.ajaxFormValidation) {
                methods._validateFormWithAjax(form, options);
                return false;
            }

            if (options.onValidationComplete) {
                options.onValidationComplete(form, r);
                return false;
            }
            return r;
        },

        /**
        * Return true if the ajax field validations passed so far
        * @param {Object} options
        * @return true, is all ajax validation passed so far (remember ajax is async)
        */
        _checkAjaxStatus: function (options) {
            var status = true;
            $.each(options.ajaxValidCache, function (key, value) {
                if (!value) {
                    status = false;
                    // break the each
                    return false;
                }
            });
            return status;
        },
        /**
        * Validates form fields, shows prompts accordingly
        *
        * @param {jqObject}
        *            form
        * @param {skipAjaxFieldValidation}
        *            boolean - when set to true, ajax field validation is skipped, typically used when the submit button is clicked
        *
        * @return true if form is valid, false if not, undefined if ajax form validation is done
        */
        _validateFields: function (form, skipAjaxValidation) {
            var options = form.data('jqv');

            // this variable is set to true if an error is found
            var errorFound = false;

            // Trigger hook, start validation
            form.trigger("jqv.form.validating");
            // first, evaluate status of non ajax fields
            form.find('[class*=validate]').not(':hidden').not(":disabled").each(function () {
                var field = $(this);
                errorFound |= methods._validateField(field, options, skipAjaxValidation);
            });
            // second, check to see if all ajax calls completed ok
            // errorFound |= !methods._checkAjaxStatus(options);

            // thrird, check status and scroll the container accordingly
            form.trigger("jqv.form.result", [errorFound]);

            if (errorFound) {

                if (options.scroll) {

                    // get the position of the first error, there should be at least one, no need to check this
                    //var destination = form.find(".formError:not('.greenPopup'):first").offset().top;

                    // look for the visually top prompt
                    var destination = Number.MAX_VALUE;
                    var fixleft = 0;
                    var lst = $(".formError:not('.greenPopup')");

                    for (var i = 0; i < lst.length; i++) {
                        var d = $(lst[i]).offset().top;
                        if (d < destination) {
                            destination = d;
                            fixleft = $(lst[i]).offset().left;
                        }
                    }

                    if (!options.isOverflown)
                        $("html:not(:animated),body:not(:animated)").animate({
                            scrollTop: destination,
                            scrollLeft: fixleft
                        }, 1100);
                    else {
                        var overflowDIV = $(options.overflownDIV);
                        var scrollContainerScroll = overflowDIV.scrollTop();
                        var scrollContainerPos = -parseInt(overflowDIV.offset().top);

                        destination += scrollContainerScroll + scrollContainerPos - 5;
                        var scrollContainer = $(options.overflownDIV + ":not(:animated)");

                        scrollContainer.animate({
                            scrollTop: destination
                        }, 1100);

                        $("html:not(:animated),body:not(:animated)").animate({
                            scrollTop: overflowDIV.offset().top,
                            scrollLeft: fixleft
                        }, 1100);
                    }
                }
                return false;
            }
            return true;
        },
        /**
        * This method is called to perform an ajax form validation.
        * During this process all the (field, value) pairs are sent to the server which returns a list of invalid fields or true
        *
        * @param {jqObject} form
        * @param {Map} options
        */
        _validateFormWithAjax: function (form, options) {

            var data = form.serialize();
            var url = (options.ajaxFormValidationURL) ? options.ajaxFormValidationURL : form.attr("action");
            $.ajax({
                type: "GET",
                url: url,
                cache: false,
                dataType: "json",
                data: data,
                form: form,
                methods: methods,
                options: options,
                beforeSend: function () {
                    return options.onBeforeAjaxFormValidation(form, options);
                },
                error: function (data, transport) {
                    methods._ajaxError(data, transport);
                },
                success: function (json) {

                    if (json !== true) {

                        // getting to this case doesn't necessary means that the form is invalid
                        // the server may return green or closing prompt actions
                        // this flag helps figuring it out
                        var errorInForm = false;
                        for (var i = 0; i < json.length; i++) {
                            var value = json[i];

                            var errorFieldId = value[0];
                            var errorField = $($("#" + errorFieldId)[0]);

                            // make sure we found the element
                            if (errorField.length == 1) {

                                // promptText or selector
                                var msg = value[2];
                                // if the field is valid
                                if (value[1] == true) {

                                    if (msg == "" || !msg) {
                                        // if for some reason, status==true and error="", just close the prompt
                                        methods._closePrompt(errorField);
                                    } else {
                                        // the field is valid, but we are displaying a green prompt
                                        if (options.allrules[msg]) {
                                            var txt = options.allrules[msg].alertTextOk;
                                            if (txt)
                                                msg = txt;
                                        }
                                        methods._showPrompt(errorField, msg, "pass", false, options, true);
                                    }

                                } else {
                                    // the field is invalid, show the red error prompt
                                    errorInForm |= true;
                                    if (options.allrules[msg]) {
                                        var txt = options.allrules[msg].alertText;
                                        if (txt)
                                            msg = txt;
                                    }
                                    methods._showPrompt(errorField, msg, "", false, options, true);
                                }
                            }
                        }
                        options.onAjaxFormComplete(!errorInForm, form, json, options);
                    } else
                        options.onAjaxFormComplete(true, form, "", options);
                }
            });

        },
        /**
        * Validates field, shows prompts accordingly
        *
        * @param {jqObject}
        *            field
        * @param {Array[String]}
        *            field's validation rules
        * @param {Map}
        *            user options
        * @return true if field is valid
        */
        _validateField: function (field, options, skipAjaxValidation) {
            if (!field.attr("id"))
                $.error("jQueryValidate: an ID attribute is required for this field: " + field.attr("name") + " class:" +
                field.attr("class"));

            var rulesParsing = field.attr('class');
            var getRules = /validate\[(.*)\]/.exec(rulesParsing);
            if (!getRules)
                return false;
            var str = getRules[1];
            var rules = str.split(/\[|,|\]/);

            // true if we ran the ajax validation, tells the logic to stop messing with prompts
            var isAjaxValidator = false;
            var fieldName = field.attr("name");
            var promptText = "";
            var required = false;
            options.isError = false;
            options.showArrow = true;

            for (var i = 0; i < rules.length; i++) {

                var errorMsg = undefined;
                switch (rules[i]) {

                    case "required":
                        required = true;
                        errorMsg = methods._required(field, rules, i, options);
                        break;
                    case "custom":
                        errorMsg = methods._customRegex(field, rules, i, options);
                        break;
                    case "ajax":
                        // ajax has its own prompts handling technique
                        if (!skipAjaxValidation) {
                            methods._ajax(field, rules, i, options);
                            isAjaxValidator = true;
                        }
                        break;
                    case "minSize":
                        errorMsg = methods._minSize(field, rules, i, options);
                        break;
                    case "maxSize":
                        errorMsg = methods._maxSize(field, rules, i, options);
                        break;
                    case "min":
                        errorMsg = methods._min(field, rules, i, options);
                        break;
                    case "max":
                        errorMsg = methods._max(field, rules, i, options);
                        break;
                    case "past":
                        errorMsg = methods._past(field, rules, i, options);
                        break;
                    case "future":
                        errorMsg = methods._future(field, rules, i, options);
                        break;
                    case "maxCheckbox":
                        errorMsg = methods._maxCheckbox(field, rules, i, options);
                        field = $($("input[name='" + fieldName + "']"));
                        break;
                    case "minCheckbox":
                        errorMsg = methods._minCheckbox(field, rules, i, options);
                        field = $($("input[name='" + fieldName + "']"));
                        break;
                    case "equals":
                        errorMsg = methods._equals(field, rules, i, options);
                        break;
                    case "funcCall":
                        errorMsg = methods._funcCall(field, rules, i, options);
                        break;
                    // Custom
                    case "checkDuplicate":
                        errorMsg = methods._checkDuplicate(field, rules, i, options);
                        break;
                    case "checkUserAvailability":
                        errorMsg = methods._checkUserAvailability(field, rules, i, options);
                        break;

                    default:
                        //$.error("jQueryValidator rule not found"+rules[i]);
                }
                if (errorMsg !== undefined) {
                    promptText += errorMsg + "<br/>";
                    options.isError = true;

                }

            }
            // If the rules required is not added, an empty field is not validated
            if (!required) {
                if (field.val() == "") options.isError = false;
            }
            // Hack for radio/checkbox group button, the validation go into the
            // first radio/checkbox of the group
            var fieldType = field.attr("type");

            if ((fieldType == "radio" || fieldType == "checkbox") && $("input[name='" + fieldName + "']").size() > 1) {
                field = $($("input[name='" + fieldName + "'][type!=hidden]:first"));
                options.showArrow = false;
            }

            if (options.isError) {

                methods._showPrompt(field, promptText, "", false, options);
            } else {
                if (!isAjaxValidator) methods._closePrompt(field);
            }
            field.trigger("jqv.field.result", [field, options.isError, promptText]);
            return options.isError;
        },
        /**
        * _checkDuplicate() //This function will check the uniqueness of the two specified form fields
        */
        _checkDuplicate: function (field, rules, i, options) {
            var equalsField = rules[i + 1];
            if (field.attr('value') == $("#" + equalsField).attr('value'))
                return options.allrules.checkDuplicate.alertText;
        },
        /**
        * _checkUserAvailability() //This function will check the uniqueness of User ID
        */
        _checkUserAvailability: function (field, rules, i, options) {
            var result = "noError";
            $.ajax({
                type: "POST",
                url: "RegistrationForm.aspx/checkUserAvailability",
                data: JSON.stringify({ userID: field.attr('value') }),
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                async: true,
                success: function (data, status) {
                    callError(data.d);
                    if (result == "Error") {
                        return options.allrules.checkUserAvailability.alertText;
                    }
                },
                failure: function (data, status) {

                },
                error: function (data, status) {

                }
            });

            function callError(data) {
                if (data == false) {
                    result = "Error";
                }
            }

            //if (result == "Error") {
            //    return options.allrules.checkUserAvailability.alertText;
            //}
        },
        /**
        * Required validation
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _required: function (field, rules, i, options) {
            switch (field.attr("type")) {
                case "text":
                case "password":
                case "textarea":
                case "file":
                default:
                    if (!field.val())
                        return options.allrules[rules[i]].alertText;
                    break;
                case "radio":
                case "checkbox":
                    var name = field.attr("name");
                    if ($("input[name='" + name + "']:checked").size() == 0) {

                        if ($("input[name='" + name + "']").size() == 1)
                            return options.allrules[rules[i]].alertTextCheckboxe;
                        else
                            return options.allrules[rules[i]].alertTextCheckboxMultiple;
                    }
                    break;
                // required for <select>
                case "select-one":
                    // added by paul@kinetek.net for select boxes, Thank you
                    if (!field.val())
                        return options.allrules[rules[i]].alertText;
                    break;
                case "select-multiple":
                    // added by paul@kinetek.net for select boxes, Thank you
                    if (!field.find("option:selected").val())
                        return options.allrules[rules[i]].alertText;
                    break;
            }
        },
        /**
        * Validate Regex rules
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _customRegex: function (field, rules, i, options) {
            var customRule = rules[i + 1];
            var rule = options.allrules[customRule];
            if (!rule) {
                alert("jqv:custom rule not found " + customRule);
                return;
            }

            var ex = rule.regex;
            if (!ex) {
                alert("jqv:custom regex not found " + customRule);
                return;
            }
            var pattern = new RegExp(ex);

            if (!pattern.test(field.val()))
                return options.allrules[customRule].alertText;
        },
        /**
        * Validate custom function outside of the engine scope
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _funcCall: function (field, rules, i, options) {
            var functionName = rules[i + 1];
            var fn = window[functionName];
            if (typeof (fn) == 'function')
                return fn(field, rules, i, options);

        },
        /**
        * Field match
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _equals: function (field, rules, i, options) {
            var equalsField = rules[i + 1];

            if (field.val() != $("#" + equalsField).val())
                return options.allrules.equals.alertText;
        },
        /**
        * Check the maximum size (in characters)
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _maxSize: function (field, rules, i, options) {
            var max = rules[i + 1];
            var len = field.val().length;

            if (len > max) {
                var rule = options.allrules.maxSize;
                return rule.alertText + max + rule.alertText2;
            }
        },
        /**
        * Check the minimum size (in characters)
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _minSize: function (field, rules, i, options) {
            var min = rules[i + 1];
            var len = field.val().length;

            if (len < min) {
                var rule = options.allrules.minSize;
                return rule.alertText + min + rule.alertText2;
            }
        },
        /**
        * Check number minimum value
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _min: function (field, rules, i, options) {
            var min = parseFloat(rules[i + 1]);
            var len = parseFloat(field.val());

            if (len < min) {
                var rule = options.allrules.min;
                if (rule.alertText2) return rule.alertText + min + rule.alertText2;
                return rule.alertText + min;
            }
        },
        /**
        * Check number maximum value
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _max: function (field, rules, i, options) {
            var max = parseFloat(rules[i + 1]);
            var len = parseFloat(field.val());

            if (len > max) {
                var rule = options.allrules.max;
                if (rule.alertText2) return rule.alertText + max + rule.alertText2;
                //orefalo: to review, also do the translations
                return rule.alertText + max;
            }
        },
        /**
        * Checks date is in the past
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _past: function (field, rules, i, options) {

            var p = rules[i + 1];
            var pdate = (p.toLowerCase() == "now") ? new Date() : methods._parseDate(p);
            var vdate = methods._parseDate(field.val());

            if (vdate < pdate) {
                var rule = options.allrules.past;
                if (rule.alertText2) return rule.alertText + methods._dateToString(pdate) + rule.alertText2;
                return rule.alertText + methods._dateToString(pdate);
            }
        },
        /**
        * Checks date is in the future
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _future: function (field, rules, i, options) {

            var p = rules[i + 1];
            var pdate = (p.toLowerCase() == "now") ? new Date() : methods._parseDate(p);
            var vdate = methods._parseDate(field.val());

            if (vdate > pdate) {
                var rule = options.allrules.future;
                if (rule.alertText2) return rule.alertText + methods._dateToString(pdate) + rule.alertText2;
                return rule.alertText + methods._dateToString(pdate);
            }
        },
        /**
        * Max number of checkbox selected
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _maxCheckbox: function (field, rules, i, options) {

            var nbCheck = rules[i + 1];
            var groupname = field.attr("name");
            var groupSize = $("input[name='" + groupname + "']:checked").size();
            if (groupSize > nbCheck) {
                options.showArrow = false;
                if (options.allrules.maxCheckbox.alertText2) return options.allrules.maxCheckbox.alertText + " " + nbCheck + " " + options.allrules.maxCheckbox.alertText2;
                return options.allrules.maxCheckbox.alertText;
            }
        },
        /**
        * Min number of checkbox selected
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return an error string if validation failed
        */
        _minCheckbox: function (field, rules, i, options) {

            var nbCheck = rules[i + 1];
            var groupname = field.attr("name");
            var groupSize = $("input[name='" + groupname + "']:checked").size();
            if (groupSize < nbCheck) {
                options.showArrow = false;
                return options.allrules.minCheckbox.alertText + " " + nbCheck + " " +
                options.allrules.minCheckbox.alertText2;
            }
        },
        /**
        * Ajax field validation
        *
        * @param {jqObject} field
        * @param {Array[String]} rules
        * @param {int} i rules index
        * @param {Map}
        *            user options
        * @return nothing! the ajax validator handles the prompts itself
        */
        _ajax: function (field, rules, i, options) {


            var errorSelector = rules[i + 1];
            var rule = options.allrules[errorSelector];
            var extraData = rule.extraData;
            var extraDataDynamic = rule.extraDataDynamic;

            if (!extraData)
                extraData = "";

            if (extraDataDynamic) {
                var tmpData = [];
                var domIds = String(extraDataDynamic).split(",");
                for (var i = 0; i < domIds.length; i++) {
                    var id = domIds[i];
                    if ($(id).length) {
                        var inputValue = field.closest("form").find(id).val();
                        var keyValue = id.replace('#', '') + '=' + escape(inputValue);
                        tmpData.push(keyValue);
                    }
                }
                extraDataDynamic = tmpData.join("&");
            } else {
                extraDataDynamic = "";
            }

            if (!options.isError) {
                $.ajax({
                    type: "GET",
                    url: rule.url,
                    cache: false,
                    dataType: "json",
                    data: "fieldId=" + field.attr("id") + "&fieldValue=" + field.val() + "&extraData=" + extraData + "&" + extraDataDynamic,
                    field: field,
                    rule: rule,
                    methods: methods,
                    options: options,
                    beforeSend: function () {
                        // build the loading prompt
                        var loadingText = rule.alertTextLoad;
                        if (loadingText)
                            methods._showPrompt(field, loadingText, "load", true, options);
                    },
                    error: function (data, transport) {
                        methods._ajaxError(data, transport);
                    },
                    success: function (json) {

                        // asynchronously called on success, data is the json answer from the server
                        var errorFieldId = json[0];
                        var errorField = $($("#" + errorFieldId)[0]);
                        // make sure we found the element
                        if (errorField.length == 1) {
                            var status = json[1];
                            // read the optional msg from the server
                            var msg = json[2];
                            if (!status) {
                                // Houston we got a problem - display an red prompt
                                options.ajaxValidCache[errorFieldId] = false;
                                options.isError = true;

                                // resolve the msg prompt
                                if (msg) {
                                    if (options.allrules[msg]) {
                                        var txt = options.allrules[msg].alertText;
                                        if (txt)
                                            msg = txt;
                                    }
                                }
                                else
                                    msg = rule.alertText;

                                methods._showPrompt(errorField, msg, "", true, options);
                            } else {
                                if (options.ajaxValidCache[errorFieldId] !== undefined)
                                    options.ajaxValidCache[errorFieldId] = true;

                                // resolves the msg prompt
                                if (msg) {
                                    if (options.allrules[msg]) {
                                        var txt = options.allrules[msg].alertTextOk;
                                        if (txt)
                                            msg = txt;
                                    }
                                }
                                else
                                    msg = rule.alertTextOk;

                                // see if we should display a green prompt
                                if (msg)
                                    methods._showPrompt(errorField, msg, "pass", true, options);
                                else
                                    methods._closePrompt(errorField);
                            }
                        }
                    }
                });
            }
        },
        /**
        * Common method to handle ajax errors
        *
        * @param {Object} data
        * @param {Object} transport
        */
        _ajaxError: function (data, transport) {
            if (data.status == 0 && transport == null)
                alert("The page is not served from a server! ajax call failed");
            else if (typeof console != "undefined")
                console.log("Ajax error: " + data.status + " " + transport);
        },
        /**
        * date -> string
        *
        * @param {Object} date
        */
        _dateToString: function (date) {

            return date.getFullYear() + "-" + (date.getMonth() + 1) + "-" + date.getDate();
        },
        /**
        * Parses an ISO date
        * @param {String} d
        */
        _parseDate: function (d) {

            var dateParts = d.split("-");
            if (dateParts == d)
                dateParts = d.split("/");
            return new Date(dateParts[0], (dateParts[1] - 1), dateParts[2]);
        },
        /**
        * Builds or updates a prompt with the given information
        *
        * @param {jqObject} field
        * @param {String} promptText html text to display type
        * @param {String} type the type of bubble: 'pass' (green), 'load' (black) anything else (red)
        * @param {boolean} ajaxed - use to mark fields than being validated with ajax
        * @param {Map} options user options
        */
        _showPrompt: function (field, promptText, type, ajaxed, options, ajaxform) {
            var prompt = methods._getPrompt(field);
            // The ajax submit errors are not see has an error in the form,
            // When the form errors are returned, the engine see 2 bubbles, but those are ebing closed by the engine at the same time
            // Because no error was found befor submitting
            if (ajaxform) prompt = false;
            if (prompt)
                methods._updatePrompt(field, prompt, promptText, type, ajaxed, options);
            else
                methods._buildPrompt(field, promptText, type, ajaxed, options);
        },
        /**
        * Builds and shades a prompt for the given field.
        *
        * @param {jqObject} field
        * @param {String} promptText html text to display type
        * @param {String} type the type of bubble: 'pass' (green), 'load' (black) anything else (red)
        * @param {boolean} ajaxed - use to mark fields than being validated with ajax
        * @param {Map} options user options
        */
        _buildPrompt: function (field, promptText, type, ajaxed, options) {

            // create the prompt
            var prompt = $('<div>');
            prompt.addClass(methods._getClassName(field.attr("id")) + "formError");
            // add a class name to identify the parent form of the prompt
            if (field.is(":input")) prompt.addClass("parentForm" + methods._getClassName(field.parents('form').attr("id")));
            prompt.addClass("formError");

            switch (type) {
                case "pass":
                    prompt.addClass("greenPopup");
                    break;
                case "load":
                    prompt.addClass("blackPopup");
            }
            if (ajaxed)
                prompt.addClass("ajaxed");

            // create the prompt content
            var promptContent = $('<div>').addClass("formErrorContent").html(promptText).appendTo(prompt);
            // create the css arrow pointing at the field
            // note that there is no triangle on max-checkbox and radio
            if (options.showArrow) {
                var arrow = $('<div>').addClass("formErrorArrow");

                switch (options.promptPosition) {
                    case "bottomLeft":
                    case "bottomRight":
                        prompt.find(".formErrorContent").before(arrow);
                        arrow.addClass("formErrorArrowBottom").html('<div class="line1"><!-- --></div><div class="line2"><!-- --></div><div class="line3"><!-- --></div><div class="line4"><!-- --></div><div class="line5"><!-- --></div><div class="line6"><!-- --></div><div class="line7"><!-- --></div><div class="line8"><!-- --></div><div class="line9"><!-- --></div><div class="line10"><!-- --></div>');
                        break;
                    case "topLeft":
                    case "topRight":
                        arrow.html('<div class="line10"><!-- --></div><div class="line9"><!-- --></div><div class="line8"><!-- --></div><div class="line7"><!-- --></div><div class="line6"><!-- --></div><div class="line5"><!-- --></div><div class="line4"><!-- --></div><div class="line3"><!-- --></div><div class="line2"><!-- --></div><div class="line1"><!-- --></div>');
                        prompt.append(arrow);
                        break;
                }
            }

            //Cedric: Needed if a container is in position:relative
            // insert prompt in the form or in the overflown container?
            if (options.isOverflown)
                field.before(prompt);
            else
                $("body").append(prompt);

            var pos = methods._calculatePosition(field, prompt, options);
            prompt.css({
                "top": pos.callerTopPosition,
                "left": pos.callerleftPosition,
                "marginTop": pos.marginTopSize,
                "opacity": 0
            });

            return prompt.animate({
                "opacity": 0.87
            });

        },
        /**
        * Updates the prompt text field - the field for which the prompt
        * @param {jqObject} field
        * @param {String} promptText html text to display type
        * @param {String} type the type of bubble: 'pass' (green), 'load' (black) anything else (red)
        * @param {boolean} ajaxed - use to mark fields than being validated with ajax
        * @param {Map} options user options
        */
        _updatePrompt: function (field, prompt, promptText, type, ajaxed, options) {

            if (prompt) {
                if (type == "pass")
                    prompt.addClass("greenPopup");
                else
                    prompt.removeClass("greenPopup");

                if (type == "load")
                    prompt.addClass("blackPopup");
                else
                    prompt.removeClass("blackPopup");

                if (ajaxed)
                    prompt.addClass("ajaxed");
                else
                    prompt.removeClass("ajaxed");

                prompt.find(".formErrorContent").html(promptText);

                var pos = methods._calculatePosition(field, prompt, options);
                prompt.animate({
                    "top": pos.callerTopPosition,
                    "marginTop": pos.marginTopSize
                });
            }
        },
        /**
        * Closes the prompt associated with the given field
        *
        * @param {jqObject}
        *            field
        */
        _closePrompt: function (field) {

            var prompt = methods._getPrompt(field);
            if (prompt)
                prompt.fadeTo("fast", 0, function () {
                    prompt.remove();
                });
        },
        closePrompt: function (field) {
            return methods._closePrompt(field);
        },
        /**
        * Returns the error prompt matching the field if any
        *
        * @param {jqObject}
        *            field
        * @return undefined or the error prompt (jqObject)
        */
        _getPrompt: function (field) {

            var className = "." + methods._getClassName(field.attr("id")) + "formError";
            var match = $(className)[0];
            if (match)
                return $(match);
        },
        /**
        * Calculates prompt position
        *
        * @param {jqObject}
        *            field
        * @param {jqObject}
        *            the prompt
        * @param {Map}
        *            options
        * @return positions
        */
        _calculatePosition: function (field, promptElmt, options) {

            var promptTopPosition, promptleftPosition, marginTopSize;
            var fieldWidth = field.width();
            var promptHeight = promptElmt.height();

            var overflow = options.isOverflown;
            if (overflow) {
                // is the form contained in an overflown container?
                promptTopPosition = promptleftPosition = 0;
                // compensation for the arrow
                marginTopSize = -promptHeight;
            } else {
                var offset = field.offset();
                promptTopPosition = offset.top;
                promptleftPosition = offset.left;
                marginTopSize = 0;
            }

            switch (options.promptPosition) {

                default:
                case "topRight":
                    if (overflow)
                    // Is the form contained in an overflown container?
                        promptleftPosition += fieldWidth - 30;
                    else {
                        promptleftPosition += fieldWidth - 30;
                        promptTopPosition += -promptHeight;
                    }
                    break;
                case "topLeft":
                    promptTopPosition += -promptHeight - 10;
                    break;
                case "centerRight":
                    promptleftPosition += fieldWidth + 13;
                    break;
                case "bottomLeft":
                    promptTopPosition = promptTopPosition + field.height() + 15;
                    break;
                case "bottomRight":
                    promptleftPosition += fieldWidth - 30;
                    promptTopPosition += field.height() + 5;
            }

            return {
                "callerTopPosition": promptTopPosition + "px",
                "callerleftPosition": promptleftPosition + "px",
                "marginTopSize": marginTopSize + "px"
            };
        },
        /**
        * Saves the user options and variables in the form.data
        *
        * @param {jqObject}
        *            form - the form where the user option should be saved
        * @param {Map}
        *            options - the user options
        * @return the user options (extended from the defaults)
        */
        _saveOptions: function (form, options) {

            // is there a language localisation ?
            if ($.validationEngineLanguage)
                var allRules = $.validationEngineLanguage.allRules;
            else
                $.error("jQuery.validationEngine rules are not loaded, plz add localization files to the page");

            var userOptions = $.extend({

                // Name of the event triggering field validation
                validationEventTrigger: "blur",
                // Automatically scroll viewport to the first error
                scroll: true,
                // Opening box position, possible locations are: topLeft,
                // topRight, bottomLeft, centerRight, bottomRight
                promptPosition: "topRight",
                bindMethod: "bind",
                // internal, automatically set to true when it parse a _ajax rule
                inlineAjax: false,
                // if set to true, the form data is sent asynchronously via ajax to the form.action url (get)
                ajaxFormValidation: false,
                // Ajax form validation callback method: boolean onComplete(form, status, errors, options)
                // retuns false if the form.submit event needs to be canceled.
                ajaxFormValidationURL: false,
                // The url to send the submit ajax validation (default to action)
                onAjaxFormComplete: $.noop,
                // called right before the ajax call, may return false to cancel
                onBeforeAjaxFormValidation: $.noop,
                // Stops form from submitting and execute function assiciated with it
                onValidationComplete: false,

                // Used when the form is displayed within a scrolling DIV
                isOverflown: false,
                overflownDIV: "",

                // --- Internals DO NOT TOUCH or OVERLOAD ---
                // validation rules and i18
                allrules: allRules,
                // true when form and fields are binded
                binded: false,
                // set to true, when the prompt arrow needs to be displayed
                showArrow: true,
                // did one of the validation fail ? kept global to stop further ajax validations
                isError: false,
                // Caches field validation status, typically only bad status are created.
                // the array is used during ajax form validation to detect issues early and prevent an expensive submit
                ajaxValidCache: {}

            }, options);

            form.data('jqv', userOptions);
            return userOptions;
        },

        /**
        * Removes forbidden characters from class name
        * @param {String} className
        */
        _getClassName: function (className) {
            return className.replace(":", "_").replace(".", "_");
        }
    };

    /**
    * Plugin entry point.
    * You may pass an action as a parameter or a list of options.
    * if none, the init and attach methods are being called.
    * Remember: if you pass options, the attached method is NOT called automatically
    *
    * @param {String}
    *            method (optional) action
    */
    $.fn.validationEngine = function (method) {

        var form = $(this);
        if (!form[0]) return false;  // stop here if the form does not exist

        if (typeof (method) == 'string' && method.charAt(0) != '_' && methods[method]) {

            // make sure init is called once
            if (method != "showPrompt" && method != "hidePrompt" && method != "hide" && method != "hideAll")
                methods.init.apply(form);

            return methods[method].apply(form, Array.prototype.slice.call(arguments, 1));
        } else if (typeof method == 'object' || !method) {
            // default constructor with or without arguments
            methods.init.apply(form, arguments);
            return methods.attach.apply(form);
        } else {
            $.error('Method ' + method + ' does not exist in jQuery.validationEngine');
        }
    };
})(jQuery);

//**************************************

02) :: jquery.ValidationEngine-en.js :: (check line 142)

(function ($) {
    $.fn.validationEngineLanguage = function () {
    };
    $.validationEngineLanguage = {
        newLang: function () {
            $.validationEngineLanguage.allRules = {
                "required": { // Add your regex rules here, you can take telephone as an example
                    "regex": "none",
                    "alertText": "* This field is required",
                    "alertTextCheckboxMultiple": "* Please select an option",
                    "alertTextCheckboxe": "* This checkbox is required"
                },
                "minSize": {
                    "regex": "none",
                    "alertText": "* Minimum ",
                    "alertText2": " characters needed"
                },
                "maxSize": {
                    "regex": "none",
                    "alertText": "* Maximum ",
                    "alertText2": " characters allowed"
                },
                "min": {
                    "regex": "none",
                    "alertText": "* Minimum value is "
                },
                "max": {
                    "regex": "none",
                    "alertText": "* Maximum value is "
                },
                "past": {
                    "regex": "none",
                    "alertText": "* Date prior to "
                },
                "future": {
                    "regex": "none",
                    "alertText": "* Date past "
                },
                "maxCheckbox": {
                    "regex": "none",
                    "alertText": "* Maximum ",
                    "alertText2": " options allowed"
                },
                "minCheckbox": {
                    "regex": "none",
                    "alertText": "* Please select ",
                    "alertText2": " options"
                },
                "equals": {
                    "regex": "none",
                    "alertText": "* Fields do not match"
                },
                "phone": {
                    // credit: jquery.h5validate.js / orefalo
                    "regex": /^([\+][0-9]{1,3}[ \.\-])?([\(]{1}[0-9]{2,6}[\)])?([0-9 \.\-\/]{3,20})((x|ext|extension)[ ]?[0-9]{1,4})?$/,
                    "alertText": "* Invalid phone number"
                },
                "email": {
                    // Shamelessly lifted from Scott Gonzalez via the Bassistance Validation plugin http://projects.scottsplayground.com/email_address_validation/
                    "regex": /^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i,
                    "alertText": "* Invalid email address"
                },
                "integer": {
                    "regex": /^[\-\+]?\d+$/,
                    "alertText": "* Not a valid integer"
                },
                "number": {
                    // Number, including positive, negative, and floating decimal. credit: orefalo
                    "regex": /^[\-\+]?(([0-9]+)([\.,]([0-9]+))?|([\.,]([0-9]+))?)$/,
                    "alertText": "* Invalid floating decimal number"
                },
                "date": {
                    "regex": /^\d{4}[\/\-](0?[1-9]|1[012])[\/\-](0?[1-9]|[12][0-9]|3[01])$/,
                    "alertText": "* Invalid date, must be in YYYY-MM-DD format"
                },
                "ipv4": {
                    "regex": /^((([01]?[0-9]{1,2})|(2[0-4][0-9])|(25[0-5]))[.]){3}(([0-1]?[0-9]{1,2})|(2[0-4][0-9])|(25[0-5]))$/,
                    "alertText": "* Invalid IP address"
                },
                "url": {
                    "regex": /^(https?|ftp):\/\/(((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:)*@)?(((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]))|((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?)(:\d*)?)(\/((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)+(\/(([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)*)*)?)?(\?((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|[\uE000-\uF8FF]|\/|\?)*)?(\#((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|\/|\?)*)?$/i,
                    "alertText": "* Invalid URL"
                },
                "onlyNumberSp": {
                    "regex": /^[0-9\ ]+$/,
                    "alertText": "* Numbers only"
                },
                "onlyLetterSp": {
                    "regex": /^[a-zA-Z\ \']+$/,
                    "alertText": "* Letters only"
                },
                "onlyLetterNumber": {
                    "regex": /^[0-9a-zA-Z]+$/,
                    "alertText": "* No special characters allowed"
                },
                // --- CUSTOM RULES -- Those are specific to the demos, they can be removed or changed to your likings
                "ajaxUserCall": {
                    "url": "ajaxValidateFieldUser",
                    // you may want to pass extra data on the ajax call
                    "extraData": "name=eric",
                    //"url": "RegistrationForm.aspx/checkUserAvailability",
                    //"extraData": "userID=a@a.com",
                    "alertText": "* This user is already taken",
                    "alertTextLoad": "* Validating, please wait"
                },
                "ajaxUserCallPhp": {
                    "url": "phpajax/ajaxValidateFieldUser.php",
                    // you may want to pass extra data on the ajax call
                    "extraData": "name=eric",
                    // if you provide an "alertTextOk", it will show as a green prompt when the field validates
                    "alertTextOk": "* This username is available",
                    "alertText": "* This user is already taken",
                    "alertTextLoad": "* Validating, please wait"
                },
                "ajaxNameCall": {
                    // remote json service location
                    "url": "ajaxValidateFieldName",
                    //"url": "RegistrationForm.aspx/checkUserAvailability",
                    // error
                    "alertText": "* This name is already taken",
                    // if you provide an "alertTextOk", it will show as a green prompt when the field validates
                    "alertTextOk": "* This name is available",
                    // speaks by itself
                    "alertTextLoad": "* Validating, please wait"
                },
                "ajaxNameCallPhp": {
                    // remote json service location
                    "url": "phpajax/ajaxValidateFieldName.php",
                    // error
                    "alertText": "* This name is already taken",
                    // speaks by itself
                    "alertTextLoad": "* Validating, please wait"
                },
                "validate2fields": {
                    "alertText": "* Please input HELLO"
                },
                // custom
                "checkDuplicate": {
                    "regex": "none",
                    "alertText": "* Duplicate entry"
                },
                "checkUserAvailability": {
                    "regex": "none",
                    "alertText": "* User ID not available",
                    "alertTextOk": "* User ID available",
                    "alertTextLoad": "* Validating, please wait"
                }
        };

    }
};
$.validationEngineLanguage.newLang();
})(jQuery);

//*************************************************

03) :: HTML ::

<asp:TextBox ID="txtbxPrimEmail" runat="server" Width="200px" MaxLength="50" title="This will be your User ID"

                        CssClass="validate[checkUserAvailability, required,custom[email]], submit, masterTooltip"></asp:TextBox>

//*************************************************

04) :: web method ::

[WebMethod]
        public static Boolean checkUserAvailability(string userID)
        {
            UserTableDatasetTableAdapters.UserTableTableAdapter userTableTableAdapter = new UserTableDatasetTableAdapters.UserTableTableAdapter();
            if (userTableTableAdapter.checkUserAvailability(userID).Equals(1))
            {
                return false;
            }
            else
            {
                return true;
            }
        }

Thanks :) Waiting for the solution very badly :(