Should I use jQuery.each()?

Question

I'm doing very frequent iterations over arrays of objects and have been using jQuery.each(). However, I'm having speed and memory issues and one of the most called methods according to my profiler is jQuery.each(). What's the word on the street about its performance? Should I switch to a simple for loop? Of course I'm fixing the many issues in my own code too.

Answer 1

This article (#3) ran some performance tests and found that the jQuery .each function was about 10x as slow as the native javascript for loop.

^{From 10 Ways to Instantly Increase Your jQuery Performance - 3. Use For Instead of Each}
Using Firebug, it's possible to measure the time each of the two functions takes to run.

var array = new Array (); for (var i=0; i<10000; i++) {     array[i] = 0; }  console.time('native'); var l = array.length; for (var i=0;i<l; i++) {     array[i] = i; } console.timeEnd('native');  console.time('jquery'); $.each (array, function (i) {     array[i] = i; }); console.timeEnd('jquery'); 

The above results are 2ms for native code, and 26ms for jQuery's "each" method. Provided I tested it on my local machine and they're not actually doing anything (just a mere array filling operation), jQuery's each function takes over 10 times as long as JS native "for" loop. This will certainly increase when dealing with more complicated stuff, like setting CSS attributes or other DOM manipulation operations.

Answer 2

The source code for jQuery's each is as follows (Thank you John Resig and MIT License):

each: function( object, callback, args ) {     var name, i = 0, length = object.length;      if ( args ) {         if ( length === undefined ) {             for ( name in object )                 if ( callback.apply( object[ name ], args ) === false )                     break;         } else             for ( ; i < length; )                 if ( callback.apply( object[ i++ ], args ) === false )                     break;      // A special, fast, case for the most common use of each     } else {         if ( length === undefined ) {             for ( name in object )                 if ( callback.call( object[ name ], name, object[ name ] ) === false )                     break;         } else             for ( var value = object[0];                 i < length && callback.call( value, i, value ) !== false; value = object[++i] ){}     }      return object; } 

As you can trace and see, in most cases it is using a basic for loop where the only overhead is really just the callback itself. Shouldn't make a difference in performance.

EDIT: This is with the realization that selector overhead has already occurred and you are given a populated array object.