There’s a good reason why. During the for loop, each option is being appended to the select. That means I’m calling jQuery to work it’s magic EVERY time within this loop. In this example, the code literally has to traverse the DOM 100 different times. Even though each option is going to the same destination! So, let’s look at it this way.
If you had to walk across a fiery pit barefooted multiple times, would you carry as much as you possibly could each time or would you continually make that trip over and over again? Personally, I’d run and not walk, but that’s just me… Hopefully, that makes some sense. Building an array full of the options and then traversing the DOM once, is infinitely more efficient. I only make a call into jQuery once. That’s an important distinction between these two techniques. Traversing the DOM using jQuery is a slow task in some regards, especially in the example above.
Feel free to play around with the code sample provided and see if you can come up with some more techniques where this same logic can be applied. It may just save you some time…