$(elem).wrapInner('<div/>') does nothing if the original element is empty.

There ''is'' some logical elbow-room here -- one could argue that the wrap shouldn't be performed if there's nothing to wrap -- but the current behavior feels like a bug to me.

Based on the syntax, the transformation is being performed on the original element, not on its children:

$(elem).wrapInner('<div/>'); // wrap the inside of this element with a div

vs.

$(elem).contents().wrapAll('<div/>'); // wrap this elements contents (if any) with a div

It's easy to get around this:

$.fn._wrapInner = $.fn.wrapInner;

$.fn.wrapInner = function(wrapper){

if(this.contents().length) return this._wrapInner(wrapper);

else return this.append(wrapper);

}

But I'd argue it ought to be changed in the library itself unless there's reason to believe a lot of folks are relying on the current behavior.