Variable becomes undefined during my function

Question

I have this jQuery function:

var searchResultsCounter = 0;
function searchPerson(filterText){
    //code
    $.ajax({
        type: "GET",
        dataType:"json",
        url: "res/main.php",
        data: { command : "loadPeople",
                filter: filterText },
        success: function( people ){
            for(var i = 0; i< people.length; i++){
                //code  
            }   
            searchResultsCounter = people.length;
            console.log(searchResultsCounter);  
        }
    }); 
console.log(searchResultsCounter);
return searchResultsCounter;
}

In the first console log, my searchResultsCoutner has a good value, at the second log, it becomes 0. Why is this happening?

Second one as in after the Ajax function? You know it is asynchronous right? So the last console.log in your code could be triggered before the one in your Ajax function. — putvande, Jul 27 '13 at 12:00
Duplicate: http://stackoverflow.com/questions/9791734/javascript-variable-scope-inside-ajax-function — krillgar, Jul 27 '13 at 12:02
possible duplicate of [How to return the response from an AJAX call?](http://stackoverflow.com/questions/14220321/how-to-return-the-response-from-an-ajax-call) — A. Wolff, Jul 27 '13 at 12:03

score 5 · Accepted Answer · answered Jul 27 '13 at 12:01

The ajax request is executed asynchronously, so the success callback function which tries to alter the variable will be executed later.

Your function simply returns 0. You have to rewrite your code that it works an asynchronous way. One way would be to pass a callback function to searchPerson as a parameter.

score 1 · Answer 2 · answered Jul 27 '13 at 12:08

1

Return from searchPerson() function the promise interface ($.ajax) and use returned result once deferred is resolved:

function searchPerson(filterText) {
    //code
    return $.ajax({
        type: "GET",
        dataType: "json",
        url: "res/main.php",
        data: {
            command: "loadPeople",
            filter: filterText
        }
    });
}

$.when(searchPerson(filterText)).done(function (data) { 
    /*SUCCESS*/
});

answered Jul 27 '13 at 12:08

A. Wolff

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and the `data` paramaeter of the function, will contain the response from `main.php`? – Victor Jul 27 '13 at 17:03
Ya, it should return data from request – A. Wolff Jul 27 '13 at 17:15

Variable becomes undefined during my function

2 Answers2