How do I access custom data attributes using JavaScript?
Jun 19, 2025 pm 11:17 PMTo access custom data properties in JavaScript, use the dataset property of the element. 1. Data attributes are custom attributes starting with data-, such as data-id, data-name, etc., used to store additional information in HTML elements; 2. In JavaScript, by selecting elements and accessing them using dataset attributes, the attribute name is removed from the data-prefix and converted to camel naming, such as data-user-role corresponding to dataset.userRole; 3. It is often used to build dynamic UIs, such as buttons perform operations based on the data stored by the element itself; 4. Note that dataset returns always a string, which needs to be manually converted to numbers or boolean values, and complex or sensitive data should not be stored.
You can access custom data attributes in JavaScript using the dataset
property of an element. This is a straightforward and efficient way to work with HTML5 data attributes.
What Are Data Attributes?
Data attributes are custom attributes you can add to any HTML element. They start with data-
, like data-id
, data-name
, or data-user-role
. These attributes are useful for storing extra information right in your HTML elements, which JavaScript can then read and use as needed.
For example:
<div id="user" data-id="123" data-role="admin">User Info</div>
How to Access Them Using JavaScript
To get the value of a data attribute, first select the element, then use the dataset
property. The name of the attribute becomes a property in dataset
, but without the data-
prefix and converted to camelCase if it contains hyphens.
Example:
const userDiv = document.getElementById('user'); console.log(userDiv.dataset.id); // Outputs: "123" console.log(userDiv.dataset.role); // Outputs: "admin"
If your attribute was named data-user-role
, it would be accessed via dataset.userRole
.
When You Might Need to Use Them
A common use case is when building dynamic UIs — for example, buttons that trigger actions based on data stored in the element itself:
<button class="delete-btn" data-id="456">Delete Item</button>
In JavaScript:
document.querySelector('.delete-btn').addEventListener('click', function() { const itemId = this.dataset.id; console.log('Deleting item with ID:', itemId); });
This avoids having to make additional server calls just to get basic info associated with an element.
Also, if you're working with templates or server-rendered pages, data attributes are a clean way to pass structured data directly into the DOM.
A Few Things to Keep in Mind
- Always remember that
dataset
returns strings. If you need numbers or JSON, you'll have to convert them manually. - Avoid storing complex or sensitive data in data attributes — they're meant for simple values.
- Hyphenated names become camelCase in
dataset
.
So if you have:
<div data-user-age="30" data-is-admin="true"></div>
Then:
element.dataset.userAge; // "30" (string) element.dataset.isAdmin; // "true" (string)
You might want to do:
const age = parseInt(element.dataset.userAge, 10); const isAdmin = element.dataset.isAdmin === 'true';
Basically that's it.
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