From what I've seen, internally jQuery is doing main_form.target (elem[ name ]) to work in all browsers, which is why the node 'target' is accessed and not the attribute.

I've found that if the type of main_form.target is not a string ( so in this case it would be a object ) you could use a different method.

I found the best way ( albeit with a for loop ) that works in all major browsers was to change line 1704 ( needs simplifying a little bit ) to:

if ( jQuery.type(elem[ name ]) === "string" )
{
	elem[ name ] = value;
}
else
{
	for ( var  i=0; i < elem.attributes.length; i++ ){
		if ( elem.attributes[i].name == name )
		{
			elem.attributes[i].value = value;
		}
	}	
}

So if the attribute it tries to access is a Dom object and not a string it uses a standard way that will work.

I've used a for loop to access the attributes as setAttribute does not work in all browsers.

Actually using:

elem.getAttributeNode( name ).nodeValue = value;

might be better than:

elem[ name ] = value;

to avoid cases where an element id/name can be a attribute of the same or another element. Seems to work in all browsers too.

Edit:

jQuery already uses elem.getAttributeNode( name ).nodeValue for getting an attribute value when an element is a form, don't see why it can't use it for setting too.

This needs to be correlated with other bugs related to the DOM providing access to form elements as direct properties of the form object.

Resetting milestone to future.

One way to is to check whether the element being accessed is a form.

In 1.5.1 something like this is done for getting an attribute, so it might be good to use for setting.

I changed from line 2062 (ish) from:

if ( value === null ) {
	if ( elem.nodeType === 1 ) {
		elem.removeAttribute( name );
	}

} else {
	elem[ name ] = value;
}

to:

if ( value === null ) {
	if ( elem.nodeType === 1 ) {
		elem.removeAttribute( name );
	}

} else {
	
	if ( set && jQuery.nodeName( elem, "form" ) ) {
		elem.setAttribute( name, value );
	} else {
		elem[ name ] = value;
	}
}

And it works fine. Only tested in Firefox so needs to be tested in other browsers but I believe it should work.

#8628 is a duplicate of this ticket.