How do you check if a selector matches something in jQuery?

Bonus tip: DIY function for streamlined code

It might be neat to extend jQuery with some special sauce, like this custom function:

$.fn.exists = function () { return this.length > 0; };
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And voila! Check element existence like a pro:

if ($(selector).exists()) {
    // Element found, let's party 🎉
}
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jQuery vs. Mootools: Battle of the selecting syntax

In the red corner, Mootools' $('selector') might return null, like a polite butler telling you something's missing. In the blue corner, jQuery always hands over an object, empty or not— that's why .length is the secret handshake in jQuery town.

jQuery met 'exists()', it was love at first sight

Adding the exists() method to jQuery's portfolio makes your conditionals crisp and clean, like a freshly ironed shirt:

if ($('#myElement').exists()) {
    // Freshly-pressed DOM manipulation coming right up
}
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Selector matching: Speed is key

$(selector).length can win races when you're in a performance showdown. It's fast, it's furious... it's the direct check. When looping faster than a hamster on a wheel, keep .length as your co-pilot.

Advanced coursework: Complex selectors and unusual suspects

In your coding journey, you'll bump into cases where selectors need to flex a bit more muscle. Here's where :has() and :contains() enter the wrestling ring:

if ($('#parent:has(.child)')) {
    // Here's childproofing jQuery style!
}

if ($('div:contains("Hide-n-Seek Champion")')) {
    // Champion found, game over!
}
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Code broken, hair pulled? Debug that jQuery!

When things go south and .length returns 0, don't rush to eBay your computer. Consider these possibilities:

• Twiddle your thumbs until the DOM is ready. Your code begs to run within $(document).ready().
• Was that a typo gremlin in your selector string?
• CSS and jQuery selectors can disagree, like cats and dogs. :visible and :hidden — remember, they're jQuery pets.
• Slow down, speed demon! Dynamic or AJAX-based content may need a little extra time to show up.

The Good, the Bad, the Deprecated: jQuery versions

With great versioning power, comes great deprecation responsibility. If you're saddled with legacy jQuery code, buckle up and navigate the jQuery migration guide for safety.

Don't go nuts extending jQuery

Yes, exists() is snazzy, but temper your enthusiasm for extending jQuery. Constructor conflicts and update woes lurk in the shadows if you don't tread carefully.