form.onchange

[Stewart]

Dear All,

I discovered last night that IE6 doesn't support the onchange event on
the form object. I had written some script in Firefox, and tested in
IE, and spent a long time trying to debug it, only to discover it is
not supported.

But I came up with a work around, which I post here for posterity:

Firefox version:
with( document.getElementById('myForm') )
{
onchange = function() { doMyStuff(); }
}

Internet Explorer version:
with( document.getElementById('myForm') )
{
for( var i = 0 ; length i ; i++ )
{
var element = elements[i];
element.priorfunc = element.onchange;
element.onchange = function()
{
var ret = true;
if( this.priorfunc )
{
ret = this.priorfunc();
}
doMyStuff();
return ret;
}
}
}

Hurrah!

Stewart
London, UK

[Stewart]

Dear All Again,

Having also noticed that IE6 does not trigger onchange for radio
buttons and checkboxes immediately, but waits until focus has moved
away from the element, this version may be more useful for exactly
duplicating Firefox's behaviour.

See also:
http://groups.google.co.uk/group/com...a2ac02da478c3e
http://groups.google.co.uk/group/com...aa1e41ff1c2f41
http://msdn.microsoft.com/library/de...s/onchange.asp

//-----------------------

with( document.getElementById('myForm') )
{
// This complexity is because Internet Explorer
// does not trigger onchange() on a form object,
// otherwise it would be this one-liner:
// onchange = function() { doMyStuff(); }
for( var i = 0 ; length i ; i++ )
{
var element = elements[i];
if(element.type == "checkbox" ||
element.type == "radio")
{
element.prioronclick = element.onclick;
element.onclick = function()
{
var ret = true;
if( this.prioronclick )
{
ret = this.prioronclick();
}
doMyStuff();
return ret;
}
element.prioronkeypress = element.onkeypress;
element.onkeypress = function()
{
var ret = true;
if( this.prioronkeypress )
{
ret = this.prioronkeypress();
}
doMyStuff();
return ret;
}
}
else
{
element.prioronchange = element.onchange;
element.onchange = function()
{
var ret = true;
if( this.prioronchange )
{
ret = this.prioronchange();
}
doMyStuff();
return ret;
}
}
}
}
Stewart
London, UK