jQuery click-function passing parameters

Question

I would like to assign the jQuery click-function for all elements in an array. But additionally, I need to access the array from within the click-function. The source will hopefully make it clearer:

for (var i=0; i<mybox.myarray.length; i++) {
    mybox.myarray[i].jqelem.click(function(event, mybox) {  
        event.preventDefault();
        doStuffWithParameter(mybox);    
    });
}   

// mybox is a JavaScript object (not jQuery-element!), myarray is an array, jqelem is a jQueryelement ala $("div.myclass");

The problem seems to be with function(event, mybox), apparently that doesn't work, i.e. mybox is unknown within the function. I think I 'kind of' understand why it cannot work this way, but how can this be achieved?

PS: I'm basically just doing it to save me from typing it manually for all array-elements.

Alnitak · Accepted Answer · 2011-08-01 19:22:30Z

3

Just remove the (useless) second callback function parameter named mybox.

If mybox is in scope in the outer block, it'll be in scope in the inner callback function too!

Should you need to know the appropriate value of i in the callback then you can do event registration-time binding:

for (var i=0; i<mybox.myarray.length; i++) {
    mybox.myarray[i].jqelem.click({i: i}, function(event) {  
        // use "event.data.i" to access i's value
        var my_i = event.data.i;
    });
}

The map {i : i} corresponds with the eventData parameter in the jQuery .click() documentation.

edited Aug 1, 2011 at 19:22

answered Aug 1, 2011 at 19:07

Alnitak

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1 Comment

Ben Over a year ago

Thank you, I didn't know that. My actual problem was related to using the i within the inner function tough, and ShankarSangoli's answer solved it for me.

Community · Accepted Answer · 2017-05-23 10:34:20Z

1

When your click handler gets called, the first argument is the event data. jQuery doesn't pass in a second argument.

Update: Using closure to get to mybox object (notice I removed the 2nd argument)

for (var i=0; i<mybox.myarray.length; i++) {
    mybox.myarray[i].jqelem.click(function(event) { 
        event.preventDefault();
        // here's the trick to get the correct i
        (function(item) {
               return function() {
                         doStuffWithParameter(mybox.myarray[item]);
               };
         })(i);

        // you can access any object from parent scope here 
        // (except i, to get to right i, you need another trick), 
        // effectively creating a closure   
        // e.g. doOtherStuff(myarray)
    });
}

Read more on closures here: http://jibbering.com/faq/notes/closures/
and here: How do JavaScript closures work?

edited May 23, 2017 at 10:34

CommunityBot

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answered Aug 1, 2011 at 19:00

Mrchief

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10 Comments

Ben Over a year ago

You're misunderstanding my question. I don't want the DOM element, I want the object. ´mybox´ is a JavaScript object, not a jQuery-element!

Ben Over a year ago

In your update, have you just removed the 2nd parameter? Cauz that doesn't do it for me. mybox is then unknown within the function.

Mrchief Over a year ago

No it is not. I just edited my answer to explain what's going on.

Ben Over a year ago

Oh, then this must be because I'm using doStuffWithParameter(mybox.myarray[i]); in my actual code? So how can I solve that?

Ben Over a year ago

Actually, ShankarSangoli's answer explains exactly this case!

|

ShankarSangoli · Accepted Answer · 2011-08-01 19:36:38Z

1

You can take help of jquery data attributes

for (var i=0; i<mybox.myarray.length; i++) {
    mybox.myarray[i].jqelem.data("arrayIndex", i).click(function(event) {  
        event.preventDefault();
        doStuffWithParameter(mybox.myarray[$(this).data("arrayIndex")]);    
    });
}

edited Aug 1, 2011 at 19:36

answered Aug 1, 2011 at 19:04

ShankarSangoli

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2 Comments

Alnitak Over a year ago

technically this answer is still incorrect - the extra callback function parameter will mask the real variable in the outer scope.

ShankarSangoli Over a year ago

Oh yeah I missed to remove that parameter, thanks @Alnitak I have edited my answer.

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