Question

var myVar = $( [] );

What does this jQuery do?

Does it initialize the variable to an empty jQuery set? I have searched the jQuery docs but haven’t found an explaination for this syntax.

Excerpt from the jQuery docs http://api.jquery.com/jQuery/

Returning an Empty Set –

As of jQuery 1.4, calling the jQuery() method with no arguments returns an empty jQuery set (with a length property of 0). In previous versions of jQuery, this would return a set containing the document node.

So could $( [] ) be a legacy method for returning an empty jQuery set or does it do something entirely different?

Answer 1

While there are different ways to interpret “legacy” (as in pst’s comment), the expression is precisely documented. We know that the $ function is the same as jQuery so looking up jQuery we see it can accept arguments in several different forms:

• jQuery( selector, [context] )
• jQuery( element )
• jQuery( elementArray )
• jQuery( jQueryObject )
• jQuery()

The one accepting an element array is documented like so:

• elementArray: An array containing a set of DOM elements to wrap in a jQuery object.

This answers your question “So could $( [] ) be a legacy method for returning an empty jQuery set or does it do something entirely different?” in the sense that no, it does not do anything different. You get a jQuery object with all the elements in your empty array. All zero of them.

And as you mentioned in your question, as of 1.4, plain ol’ $() gives you the empty set and so I take it that it may be the preferred way to do things now. That said, $([]) is nice and explicit, and still supported.