Question

Is this line

$(this).attr("id").replace("_button","");

equivalent to this one?

this.attr("id").replace("_button","");

Answer 1

since this always contains a reference to the object of invocation, it really depends where you call that code.

If you call this within a jQuery event handler, this is a reference to the DOM element itself, so you need to translate it into a jQuery object by calling $() before you can call jQuery methods on it. That in turn means

this.attr("id").replace("_button","");

will not work there.

If you’re writting a plugin method for instance, this already IS a jQuery object (reference) and both lines would actually do the same. Of course, if this already is a jQuery object you doing extra work, trying to parse it again.

example:

$.fn.yourplugin = function(){
     // this refers to a jQuery object
     return this.each(function(i,v){
     });
});