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Answer 1

+2 A:

my is a global, so by the time the click event is triggered, it will always refer to the object returned by the last call.

You could make my local and define the click function inside the obj constructor.

Uh Clem 2010-03-26 23:12:24

Answer 2

+1 A:

When you assign a function to a DOM element property like onclick, the this in that function (when invoked) is going to be the DOM element. You can change that, however, by using apply and/or a little closure.

Check this out (it is still pretty much like your example, but see the comments for what is going on now):

<script type="text/javascript">
// Obj with properties of its own, including a cool DOM object
function Obj(domobj, name) {
    this.name = (typeof name==='undefined') ? 'Clemens Prerovsky' : name;
    this.o = domobj;
    // Closure time! Preserve this 'this', using 'that'
    var that = this;
    domobj.onclick = function () {return that.clickHandler();};
}
// Handler of clicks
Obj.prototype.clickHandler = function () {
    alert(this.o.innerHTML+', name:'+this.name);
}

// Create objects with references
$(document).ready(function() {
    var o1 = new Obj(document.getElementById('b1'));
    var o2 = new Obj(document.getElementById('b2'), 'npup');
});
</script>

I urge you not to create global variables by mistake. Take care and declare your variables so you don't get so many nasty surprises. What was left of that in this example were the o1 and o2 objects.

Nasty surprises always lurk when creating circular references, and you run the risk of memory leakage if they are not handled propertly. Are the "custom objects" really needed in this manner?

HTH.

npup 2010-03-27 00:02:57

Hi guys - thanks for your help. Obviously I did not understand how to use closures in the right way, despite creating a global variable by accident :-/.The custom objects are needed, as they represent individual instances of an inline editor, with various setups (different formatting buttons etc.).Anyway - now I got the point - thank you very much!

cduke 2010-03-28 10:17:03

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JS onclick triggers wrong object

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