return found objects count

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i have txt file that store json objects

XML

[{"id":2,"name":"ahmed","dept":2},{"id":3,"name":"Mohammed","dept":2},{"id":4,"name":"Mahmoud","dept":3},{"id":5,"name":"hanan","dept":"2"},{"id":6,"name":"mona","dept":"1"},{"id":7,"name":"nadia","dept":"2"},{"id":8,"name":"sara","dept":"1"},{"id":9,"name":"mai","dept":"0"},{"id":10,"name":"nasr","dept":"1"},{"id":11,"name":"alaa","dept":"3"},{"id":12,"name":"hosni","dept":"2"}]


the code

 function empPerDept(did) {
        var total = 0;
        $.getJSON("test.txt", function (emps) {
            for (var i = 0; i < emps.length; i++) {
                if (emps[i].dept == did) {
                    total++;
                }
            }
            alert("total inside" + total);//return correct result 5 excutes after outer total
        });
        alert("total outside" + total);//aways return 0 and excutes before inside total 

    }

the problem is that console.log outputs undefined ,however count is 5 inside handler of getJson method

what is problem and how to solve

Posted 5-Mar-15 11:19am

TheSniper105

Updated 5-Mar-15 22:13pm

v2

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2 solutions

Solution 1

Your JSON string represents an array. Arrays have one additional feature compared to other objects: they have predefined property length:

JavaScript

var length = emps.length;

More generally, it's not clear why using $.each at all, to make the code heavier than it can be. You could simply write:

JavaScript

for(var element in emps)
   doSomethingWithElement(element); // for example

—SA

Posted 5-Mar-15 12:26pm

Sergey Alexandrovich Kryukov

Comments

TheSniper105 5-Mar-15 19:17pm

this is not what i want
i want yo get the employees count in depratment i pass to function
ex if i pass 2 to the function empPerDept then that function will return total count of employees in department 2

like select Count(*) from emp where dept=2 can u help

Sergey Alexandrovich Kryukov 5-Mar-15 19:27pm

How it could be the different value? Okay, the execute it all through the loop, I've demonstrated how to do it. And calculate whatever you want.
—SA

TheSniper105 6-Mar-15 4:14am

see update code the problem now is return total

Sergey Alexandrovich Kryukov 6-Mar-15 8:39am

And what is that problem? (By the way, in most cases, it's better to use ===, not ==.)
Your result depends on the value of did.
What count 5?
—SA

TheSniper105 6-Mar-15 15:57pm

number of employee in that department is stored in total variable (did short for department id )

Sergey Alexandrovich Kryukov 6-Mar-15 16:13pm

This happens because Ajax request is asynchronous. You need to pass your function as 3rd parameter, success, not data. Success is called when the Ajax request is complete, successful HTTP response is complete and parsed to the object.
—SA

TheSniper105 6-Mar-15 16:39pm

yeas that is the problem Ajax request is asynchronous can you post solution so any one can benefit from solution

Sergey Alexandrovich Kryukov 6-Mar-15 18:53pm

Ah... sorry, I feel I almost confused you because I did not pay another attention for this "return" aspect.
Here is the thing: you cannot get return this way at all. When you return before the HTTP request/response cycle, too early. This API is not designed for return at all.
That said, instead of return, you need to do all the use of the data in the callback, as you could see in those code samples. You cannot just return result. You can use it when it's ready, say, make it some value of innerHTML of some element...

Why? you can understand the idea if you see how AJAX is standardized: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest.

Are you getting it now?

—SA

TheSniper105 10-Mar-15 1:23am

yeas thank you i found that the only solution is making ajax call is synchronous

Sergey Alexandrovich Kryukov 10-Mar-15 1:28am

Right. Will you accept my answer formally now.
—SA

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TheSniper105 · Accepted Answer · 2015-03-09T19:27:00

JavaScript

function countEmps(did) {
            var empsCount = 0;
            $.ajax({
                type: 'GET',
                url: 'test.txt',
                dataType: 'json',
                async: false,
                success: function (employess) {
                    for (var i = 0; i < employess.length; i++) {

                        if ((Number(employess[i].dept)) == (Number(did))) {
                            empsCount++;
                        }
                    }
                }
            });
            return empsCount;
        }