Sentry Answers>JavaScript>

Get the ID of an element using jQuery

Get the ID of an element using jQuery

David Y.

The ProblemJump To Solution

How can I get the id of an element using jQuery? I’ve tried the following code:

Click to Copy
element = $('#test'); // select element with ID 'test' console.log(element.id); // prints "undefined" to the browser console

Why doesn’t this work and what should I do instead?

The Solution

When we invoke a jQuery selector like $('#test'), it returns an array of elements that match the selector. In the code above, an array containing all elements with the id ‘test’ will be stored in element. We can subscript this object to get individual elements (e.g. $('#test')[0]) or apply methods to all elements in the array (e.g. $('#test').hide()).

Because HTML ids must be unique, the array returned by $('#test') will only ever contain one element. As many of jQuery’s most common methods, such as hide() work on both individual elements and arrays, it usually doesn’t matter whether we’re working with a single element or an array. However, as the arrays returned by jQuery do not have an id attribute, attempting to access $('#test').id will return undefined.

We can access the element’s id in one of two ways:

  1. Subscripting the array:
    Click to Copy
    element = $('#test'); // select element with ID 'test' console.log(element[0].id); // prints "test" to the browser console
  2. Using jQuery’s attr method on the returned array:
    Click to Copy
    element = $('#test'); // select element with ID 'test' console.log(element.attr('id')); // prints "test" to the browser console

Note that the plain JavaScript equivalent of a jQuery ID selector, getElementById() will not present the same problem, as it always returns a single element. We can achieve the same results as above with the following non-jQuery JavaScript code:

Click to Copy
element = document.getElementById('test'); console.log(element.id);
  • ResourcesImprove Web Browser Performance - Find the JavaScript code causing slowdowns
  • ResourcesJavaScript Frontend Error Monitoring 101
  • Syntax.fm logo
    Listen to the Syntax Podcast

    Tasty treats for web developers brought to you by Sentry. Get tips and tricks from Wes Bos and Scott Tolinski.

    SEE EPISODES

Loved by over 4 million developers and more than 90,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.

© 2024 • Sentry is a registered Trademark
of Functional Software, Inc.