Suggest adding .length property to WidgetSet instances

[dante]

Because WidgetSet doesn't return a real (or subclassed) array like NodeList, it is overly verbose to do the most simple of tasks: determine if there are any matches.

eg:

var sublist = dijit.registry.filter(function(w){ return w.value == someinput.value });

to determine if there are any instances in the sublist new WidgetSet, you'd have to make a new variable, run .forEach and increment the variable, then check that.

var count = 0;
var sublist = (...).forEach(function(w){ count++ });
if(count){ ... }

Seems convoluted, but by maintaining a .length member on the instance, the above can be reduced to:

if(dijit.registry.filter(function(w){ return w.value == input.value }).length){
  // we pass the 'duplicate value' test!
}

Attached is an ubersimple changeset adding in the functionality. By utilizing the existing .add and .remove api's (the only way to manipulate the widgetSet) the task is trivial.

Will update campus docs to include addition pending approval.

[bill]

Sure, sounds fine, go for it. I guess there should be a unit test too though. See also #4122.

[bill]

PS: although it would be better (at least for your example) to just have some() and every() methods.

[dante]

uhh, why is [1,2,3].splice(-1) returning empty array in IE6?

[dante]

nm, patch updated. Meant to use [].slice(-1)

[dante]

will add .every and .some and tests, and commit. Thanks for the review @bill

[dante]

updated with some, every and toArray

[Les]

I have a minor improvement suggestion:

remove: function(/*String*/ id){ 	 
	//              Remove a widget from this WidgetSet. Does not destroy the widget; simply 
	//              removes the reference. 
	if(this._hash[id]){
		delete this._hash[id]; 
		this.length = Math.max(0, this.length - 1); 
	}
},

[dante]

if we add the if(this._hash[id]) the Math.max() is not required (it will never decrement unless the id is found) ... seems leaving out the if() check would be adequate in this case, but yes, alex had suggested max(0, --length) so it can never reach -1

[Les]

I was trying to prevent a situation where calling remove() with an id of a widget that was already removed would decrement length. If there's no if(), it's possible to decrease length w/o removing a widget by making multiple remove() calls with the same id parameter.

[dante]

@Les - good point. I should have considered that. Will adjust.

[dante]

(In [17529]) fixes #9290 - adding .length property, .some and .every functions, makes .forEach return instance, allows thisObj passed to forEach some and every, adding toArray method as well as .map \!strict