jQuery Element Existence: Complete Guide

No, jQuery does not have a built-in “exists” function. The most common and reliable way to check if an element exists in jQuery is by using the .length property of the jQuery collection returned by your selector, which is exactly what your current code does. However, there are several alternative approaches and plugins you can consider for a more elegant solution depending on your specific needs.

Contents

• The Standard .length Property Method
• Alternative Approaches and Simplifications
• Creating Custom jQuery Plugins
• Third-Party Plugin Options
• When You Don’t Need to Check Element Existence
• Best Practices and Recommendations

The Standard .length Property Method

Your current approach using $(selector).length > 0 is actually the standard and recommended method in jQuery. According to the official jQuery Learning Center, this is the proper way to check element existence.

if ($('#myElement').length > 0) {
    // Element exists
}

The .length property returns the number of elements that match the selector:

• Returns 0 if no elements match (falsy)
• Returns a number > 0 if elements match (truthy)

As Stack Overflow discussions confirm, this approach is reliable and works consistently across all browsers. The jQuery collection itself will never be undefined, so you won’t get errors trying to access the .length property.

Alternative Approaches and Simplifications

While your current code is perfectly valid, there are a few ways to simplify it for cleaner syntax:

Direct Length Check

You can omit the > 0 comparison since 0 is falsy and any positive number is truthy:

if ($('#myElement').length) {
    // Element exists
}

Boolean Conversion

Some developers prefer to explicitly convert to boolean:

if (!!$('#myElement').length) {
    // Element exists
}

Using .size() Method

jQuery also provides a .size() method that does the same thing as .length, though .length is more commonly used and slightly more performant:

if ($('#myElement').size()) {
    // Element exists
}

As SitePoint explains, both .length and .size() work effectively for checking element existence, but .length is the preferred approach.

Creating Custom jQuery Plugins

If you prefer a more elegant syntax, you can create custom jQuery plugins. Here are a couple of popular approaches:

Simple Exists Function

Create a standalone function that returns a boolean:

function exists(selector) {
    return $(selector).length > 0;
}

// Usage
if (exists('#myElement')) {
    // Element exists
}

jQuery Plugin with Callback

For a more jQuery-like approach, you can extend the jQuery prototype:

// Simple plugin
$.fn.exists = function() {
    return this.length > 0;
};

// Usage
if ($('#myElement').exists()) {
    // Element exists
}

Advanced Plugin with Callback

As shown on CSS-Tricks, you can create a more sophisticated plugin that accepts a callback:

$.fn.exists = function(callback) {
    var args = [].slice.call(arguments, 1);
    if (this.length) {
        callback.call(this, args);
    }
    return this;
};

// Usage
$('#myElement').exists(function() {
    // This runs only if element exists
    $(this).addClass('highlight');
});

This approach chains nicely and provides more flexibility in how you handle existing elements.

Third-Party Plugin Options

If you don’t want to write your own plugin, there are some third-party options available:

jquery-exists Package

There’s an npm package called jquery-exists that provides this functionality. However, based on the npm registry, this package appears to be largely dormant and hasn’t been updated in many years.

Checking Plugin Existence

If your question extends to checking if jQuery plugins themselves exist (rather than DOM elements), you can use the typeof operator:

// Check if a jQuery plugin exists
if (typeof $.fn.marquee === "function") {
    // Plugin exists, use it
    $('#myElement').marquee();
}

As Stack Overflow explains, this is the modern approach since jQuery’s isFunction() method was deprecated in version 3.3.

When You Don’t Need to Check Element Existence

An important insight from the official jQuery documentation is that it isn’t always necessary to test whether an element exists. jQuery methods are designed to handle non-existent elements gracefully:

// This works fine even if #myElement doesn't exist
$('#myElement').hide();
$('#myElement').addClass('hidden');

The code above will simply do nothing if the element doesn’t exist, without throwing errors. This can make your code cleaner and more readable in many cases.

As noted in multiple sources, only check for element existence when you need to:

• Handle different logic for existing vs. non-existing elements
• Load resources conditionally (like external scripts)
• Apply different behaviors based on element presence

Best Practices and Recommendations

Based on the research findings, here are the best practices for checking element existence in jQuery:

Recommended Approach

Stick with the .length property method as it’s:

• Standard practice - widely documented and recommended
• Reliable - works consistently across all browsers
• Performant - minimal overhead compared to other methods
• Readable - clearly communicates intent

if ($('#myElement').length) {
    // Element exists
}

When to Consider Alternatives

Consider creating a custom plugin when:

• You need to check element existence frequently throughout your codebase
• You want more elegant, readable syntax
• You need callback functionality for existing elements

Code Organization

If you do create custom functions or plugins:

• Keep them in a centralized utility file
• Document them clearly for your team
• Consider using jQuery’s $.extend() or $.fn.extend() for proper namespacing

Performance Considerations

For performance-critical applications:

• Use .length directly (simpler than function calls)
• Cache your jQuery selectors when using them multiple times
• Consider vanilla JavaScript alternatives like document.querySelector() for simple existence checks

As Chris Pietschmann notes, vanilla JavaScript methods can be more performant if you don’t need the full jQuery functionality.

Sources

1. Official jQuery Learning Center - How do I test whether an element exists?
2. GeeksforGeeks - How to check element exists or not in jQuery
3. SitePoint - jQuery Check if an Element Exists
4. CSS-Tricks - Check if Element Exists
5. Stack Overflow - Check if element exists in jQuery
6. Stack Overflow - Is there an “exists” function for jQuery?
7. Mkyong.com - Check if element exists in jQuery
8. npm - jquery-exists package
9. Kevin Leary - jQuery Check if Element Exists
10. Chris Pietschmann - Check if element exists using JavaScript or jQuery

Conclusion

jQuery does not have a built-in “exists” function, making your current approach using $(selector).length > 0 the standard and recommended method. While this works perfectly fine, you have several options if you prefer more elegant syntax: create custom functions, jQuery plugins, or consider third-party packages.

The .length property remains the most reliable and performant solution, but custom plugins can improve code readability and maintainability in larger projects. Remember that jQuery methods often handle non-existent elements gracefully, so only check for existence when your logic truly requires different behavior based on element presence.

For most use cases, your current code is already optimal, but the custom plugin approaches shown above can make your jQuery code more readable and consistent with other jQuery method calls.