how to pass multiple id of FileUpload to javascript function

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ASP.NET

Javascript

File-Upload

I am working on asp.net web application in which i have 6 FileUpload Controls. for one file upload i have created a javascript method to check file extension and file size. but how to pass id of FileUpload upload as a parameter so that only in only one method i can validate all FileUpload my code of javacript is

var validFilesTypes = ["bmp", "gif", "png", "jpg", "jpeg", "doc", "docx",         "xls", "xlsx", "htm", "html", "rar", "zip", "txt", "pdf"];
    function CheckExtension() {
        /*global document: false */
        var file = document.getElementById("<%=txtTenderDoc.ClientID%>");
        var path = file.value;
        var ext = path.substring(path.lastIndexOf(".") + 1, path.length).toLowerCase();
        var isValidFile = false;
        for (var i = 0; i < validFilesTypes.length; i++) {
            if (ext == validFilesTypes[i]) {
                isValidFile = true;
                break;
            }
        }
        if (!isValidFile) {
            alert("Invalid File. Unknown Extension Of Tender Doc" + "Valid extensions are:\n\n" + validFilesTypes.join(", "));
        }
        return isValidFile;
    }

    function validateFileSize() {
        /*global document: false */
        var file = document.getElementById("<%=txtTenderDoc.ClientID%>");
        var fileSize = file.files[0].size;
        var isValidFile = false;
        if (fileSize !== 0 && fileSize <= 25214400) {
            isValidFile = true;
        }
        if (!isValidFile) {
            alert("File Size Should be Greater than 0 and less than 25 mb");
        }
        return isValidFile;
    }

and i have used this in aspx page

<asp:FileUpload ID="txtTenderDoc" onchange="var result= CheckExtension();validateFileSize(); return result"
                        runat="server"></asp:FileUpload>

as you can see i have to create 6 method by this to check file size and file extension how to do that in only one method....

Updated
after seeing this


i have changed my javascript to

var validFilesTypes = ["bmp", "gif", "png", "jpg", "jpeg", "doc", "docx", "xls", "xlsx", "htm", "html", "rar", "zip", "txt", "pdf"];
        function CheckExtension(Id) 
        {
            /*global document: false */
            var file = document.getElementById(Id);
            debugger;
            var path = file.value;
            var ext = path.substring(path.lastIndexOf(".") + 1, path.length).toLowerCase();
            var isValidFile = false;
            for (var i = 0; i < validFilesTypes.length; i++) {
                if (ext == validFilesTypes[i]) {
                    isValidFile = true;
                    break;
                }
            }
            if (!isValidFile) {
                alert("Invalid File. Unknown Extension Of Tender Doc" + "Valid extensions are:\n\n" + validFilesTypes.join(", "));
            }
            return isValidFile;
        }


        function validateFileSize(Id) {
            /*global document: false */
            var file = document.getElementById(Id);
            var fileSize = file.files[0].size;
            var isValidFile = false;
            if (fileSize !== 0 && fileSize <= 25214400) {
                isValidFile = true;
            }
            if (!isValidFile) {
                alert("File Size Should be Greater than 0 and less than 25 mb");
            }
            return isValidFile;
        }

and calling it like this

<asp:FileUpload ID="flTenderDoc" onchange="var result=CheckExtension('flTenderDoc');validateFileSize('flTenderDoc'); return result"
                            runat="server"></asp:FileUpload>

but it is not working ......
can anyone help this is my first javascript method :)