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HTML Data Attributes: Custom data-* Values

Data Attributes: Custom data-* Values: The result depends on browser support and, in examples with script elements, on JavaScript being allowed. Includes a practical HTML example and an explanation.

1 views Published Oct 19, 2026 Updated Oct 19, 2026 Admin

A useful interface does not need to be complicated. Start with native HTML, then add JavaScript only when you need it.

What You Need to Know


Data attributes let you attach small custom values to HTML, such as data-product-id. JavaScript can read them through dataset, but they are visible to visitors and should not contain secrets.

In this example: add data-product-id to a button.

Try the Example


Take a look at the example. We’ll explain the important lines right below it.

<button type="button" data-product-id="sku-205" id="choose-product">Choose notebook</button>
<script>
    const productButton = document.querySelector("#choose-product");
    console.log(productButton.dataset.productId);
</script>

Let’s Read the Code


  • <button>: The button offers an action; its type or command determines what happens.
  • <script>: Script contains JavaScript, data, or other browser-understood script formats depending on type.
  • type: Type changes what sort of control or resource the browser uses.
  • id: An id uniquely identifies an element on this page.

Read the named elements and attributes together. They explain how the browser connects this feature to the rest of the page.

What Happens in the Browser?


When this example includes JavaScript, it supplies behavior that ordinary HTML does not automatically provide. Always think about a fallback.

What makes it interactive? Look for the JavaScript that finds an element and reacts to an event. HTML provides the initial controls and content; the script updates the page. Try removing the script to see which part still works natively.

Your Turn


Run this on a local development server if it loads modules or resources. Change the visible text or trigger and check what still works with scripts disabled.

Common Beginner Mistakes


  • Assuming new HTML syntax works in every browser without testing.
  • HTML supplies structure; JavaScript is necessary for the scripted behavior in this example. Check keyboard access and focus movement too.

Key Takeaways


  • Data attributes let you attach small custom values to HTML, such as data-product-id.
  • <button>: The button offers an action; its type or command determines what happens.
  • Test the behavior you expect rather than trusting how the snippet looks in your editor.
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