Get the ID of an element using jQuery

David Y.

—December 15, 2023

The Problem

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

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:
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   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:
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   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:

element = document.getElementById('test');
console.log(element.id);