Hi.
snapper:
> How can I get object reference instead of window reference in
> this.handleEvent(evt)?
>
> I have ECMAScript in a Batik SVG application using widgets. I noticed that
> the Carto textbox does not work in Batik due to event handing problems, so I
> am rewriting it. Andreas attached event handlers using the root element in
> all cases, which causes many problems. I am attaching events to the widget
> elements instead like this:
>
> this.textboxRect.addEventListener("click",this._handleEvent,false);
>
> The event handler in the textbox object does receive the event, but inside
> the this.handleEvent(evt), the "this" refers to the window object. We really
> want the reference to the textbox object.
>
> How can I get the reference to the textbox object inside the event handler
> in this case?
This is normal behaviour: when you refer to this._handleEvent, it is
just a reference the function that has been stored in the 'this'
object–it has lost its association with the object. If you want to be
able to access the 'this' object from _handleEvent, you can refer to
the object from the closure when you assign it. For example:
blah._handleEvent = function(evt) {
// refer to 'blah' in here
};
I often use a function to bind the the 'this' variable to an object of
my choosing, so that I can do what you want to do.
function bind(_this, f) {
var _ = function() {
return f.apply(_this, arguments);
};
_.toString = function() {
return "/* bound function */\n" + String(f);
};
return _;
}
and then:
blah._handleEvent = bind(blah, function() {
// now 'this' inside here will always refer to 'blah',
// regardless of how the function was called.
});
--
Cameron McCormack, http://mcc.id.au/
xmpp:[EMAIL PROTECTED] ▪ ICQ 26955922 ▪ MSN [EMAIL PROTECTED]
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
