When is the function executed when using jQuery .each()?

Question

Given the following jQuery expression

    $("form").each(function () {
        var info = validationInfo(this);
        if (info) {
            info.attachValidation();
        }
    });

The selector chooses all forms on the page, and then for each 'form' found, it attaches a function.

My question is when does the JS in this function actually run? Does the JS in the function execute when it is attached?

I think you need to enlighten us about what `validationInfo()` and `attachValidation()` are before we can answer that question. — Brad Christie, Dec 22 '10 at 20:19
I appreciate all the answers thus far. It seems I have submitted a bad example. I would like to update that with a better one (I think it is anyway), but it would invalidate the posts that have already been given. Should I start a different thread? Or should I edit the code in the original question? Not sure of the protocol — John Livermore, Dec 22 '10 at 21:29
Just to clarify: the `.each()` method does not "attach" the function to each form. It just execute the function. When binding events the term "attaches a function" is correct, that's not the case here. The `.each()` just iterates through a collection - nothing more, nothing less. — Shadow The GPT Wizard, Oct 11 '11 at 11:03

score 2 · Answer 1 · answered Dec 22 '10 at 20:18

2

When is attachValidation() ran? It's executed as soon as it's called in the loop.

answered Dec 22 '10 at 20:18

simshaun

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What more was I supposed to say? It was a rather simple question deserving a rather simple answer. – simshaun Dec 22 '10 at 20:21

score 2 · Accepted Answer · edited May 23 '17 at 12:18

It all depends where that code is located.

It will run if you include that code block in a $(function(){...} block which runs when the document is parsed:

$(function(){
    $("form").each(function () {
        var info = validationInfo(this);
        if (info) {
            info.attachValidation();
        }
    });
})

Though based on your use case, you may want to validate all forms when a user event happens like clicking a button. In that case you'd have to include the code in a function which you execute when the user clicks a button:

//Bind function to button
$("#mybutton").live('click', doValidation);

//Do validation
function doValidation() {
    $("form").each(function () {
        var info = validationInfo(this);
        if (info) {
            info.attachValidation();
        }
    });
}

"That code alone will never run per se."...sure it will, if it's located after any `
` elements...your first line is an incorrect statement. — Nick Craver, Dec 22 '10 at 20:28
Fair enough. Point being it all depends where the code is placed.. updated the post.. — Marcus Leon, Dec 22 '10 at 20:31

When is the function executed when using jQuery .each()?

2 Answers2