Not all JavaScript loops are identical. Try the code below by pasting the HTML in this tip into a file and then opening the file in your browser. You should find that the Duffs method provides the best optmization, while the second best optimization involves instantiating length in a variable and locally validating with it in the loop.

The optimization works for all common browsers, such as FireFox, IE, etc.

JavaScript loop speed test
Loops through 10000 div elements in different ways. The time required for each loop is presented below in milliseconds.
 
Loop: for (var i=0; i
for (var i=0; divs[i]; i++)
for (var i=0, il=divs.length; i
for duffs method 

Charlie Frank

Charlie has over a decade of experience in website administration and technology management. As the site admin, he oversees all technical aspects of running a high-traffic online platform, ensuring optimal performance, security, and user experience.