Is there any reason to create a local $(this) variable in a function?

Question

Do I save any memory or performance if I do this

function foo(){
   var $this = $(this);
   var class = $this.class();
   var attr = $this.attr();
}

Over this

function foo(){
   var class = $(this).class();
   var attr = $(this).attr();
}

You can use it for performance reason, executing a function take time. — jcubic, May 18 '15 at 17:50
Every time you call `$(this)` you're making an extra function call and allocating more memory. — Barmar, May 18 '15 at 17:50

score 1 · Accepted Answer · answered May 18 '15 at 17:50

The performance difference may be minimal for simple applications, but it exists. Consider that $() is a function, so any time you invoke that function the engine has to execute the code within that function. Referencing an existing variable is going to be a lot faster than executing that potentially large function.

To put it another way, this:

var x = someFunction();
someOtherFunction(x);

will always be faster than this:

someFunction();
someOtherFunction(someFunction());

Is there any reason to create a local $(this) variable in a function?

1 Answers1