Hello,
this is a JavaScript question, but one that I bump into once in a while when
developing with qooxdoo.
Test the following code in the playground:
var vbox = new qx.ui.container.Composite( new qx.ui.layout.VBox(5));
this.getRoot().add(vbox);
var data = {
"one": { label: "One" },
"two" : { label: "Two" },
"three":{ label: "Three" },
"four":{ label: "Four" },
"five":{ label: "Five" }
};
for( var key in data )
{
var button = new qx.ui.form.Button( data[key].label );
vbox.add(button);
// this doesn't work
button.addListener("execute",function(){
alert("Bad:" + data[key].label);
},this);
// this works but is a nasty hack
eval('button.addListener("execute",function(){'+
'alert("Good:"+data["'+ key+ '"].label);'+
'},this);');
}
What I am trying to achieve is to get a local variable ('key') that is the
product of the iteration through the keys of an object into a closure (here:
an event listener). The problem is that when the event listener is called,
the variable "key" evaluates to the last value it had when the iteration was
completed, not to the value it had when the even listener was created. The
only solution I could come up after a lot of experimenting was to use an
ugly eval. Does anyone have a better idea?
Thanks,
Christian
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