Iterate Counter Inside jQuery .each() Loop

Question

I need to increment a var counter inside an $.each() loop. Here's my code:

ajaxCreateOrder = function(fileUrl, dataArray, numRecords) {
    var loopIteration = 1;
    var ajaxIterateDelay = 1000;
    $.each(dataArray, function(key,val) {
        setTimeout(function() {
            doAjaxRequest(loopIteration, fileUrl, val, numRecords);
        }, loopIteration * ajaxIterateDelay);
        loopIteration++;
    });
}

All is working as expected, except that loopIteration does not increment. What am I doing wrong? Thanks.

Arun P Johny · Accepted Answer · 2013-11-26 11:45:16Z

1

It is because of wrong use of a closure variable in loop

ajaxCreateOrder = function (fileUrl, dataArray, numRecords, storeView) {
    var ajaxIterateDelay = 1000;
    $.each(dataArray, function (index, val) {
        setTimeout(function () {
            doAjaxRequest(index + 1, fileUrl, val, numRecords);
        }, (index + 1) * ajaxIterateDelay);
    });
}

Assuming dataArray is an array, the first argument is the index, you can use it

answered Nov 26, 2013 at 11:45

Arun P Johny

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3 Comments

Andreas Over a year ago

It is because of wrong use of a closure variable in loop - It's just a simple multiplication to get the timeout for setTimeout. There is no variable which is evaluated when the loop has finished...

Arun P Johny Over a year ago

@Andreas loopIteration is used inside the setTimeout() which pauses a problem because it will have the last value of the loop

Arun P Johny Over a year ago

@Andreas problem solution

Roko C. Buljan · Accepted Answer · 2013-11-26 11:48:11Z

1

    setTimeout(function() {
        // ...
        loopIteration++;                   // inside
    }, loopIteration * ajaxIterateDelay);
                                           // not here

answered Nov 26, 2013 at 11:48

Roko C. Buljan

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1 Comment

Jongosi Over a year ago

Thank you, that could be it :)

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