Each-Scoping in jQuery

Recently, I started getting away from the jQuery pattern of checking the length of an object before writing code. Instead, I've found myself wrapping my selector in jQuery's each method, and writing my code inside the function.

For example, instead of this:

if ($('.target').length) {
    var target = $('.target');
 
    // Do something with target and its children 
    target.find('.child').doSomething();
    // etc. 
}

I've been writing this:

$('.target').each(function() {
    var target = $(this);
 
    // Do something with target and its children 
    target.find('.child').doSomething();
    // etc. 
});

This has several advantages.

  1. Variables get scoped correctly: Javascript does not have block-scoping, which means that variables declared in an if statement are actually retained outside of the if statement. Using a function with each means variables declared in the function stay in the function.

  2. Multiple elements handled properly: Even if I think that there's only one element with class .target, I'm protected from failing code if there are more. Multiple .targets will work just as well as a single one in this case, even to the point that each gets its own set of locally scoped variables.

  3. Handles the no-element case: In the first code snippet, I explicitely test to see if the element exists before running the code. This is a good thing because a script file is often loaded on every page, but .target may only be on a few of those pages. The second code snippet also handles the situation that .target does not exist on a given page just as well.

While it may be odd to see an each block when only expecting a single item, the each-scoping method works as well as or better than the if-length method, and is just as short to write. It's a win in my book.