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HTML/CSSBeginner#html#elements
HTML/CSSBeginner#html#javascript
What is a data attribute and how is it used?
Custom data-* attributes let you embed extra information directly in HTML elements for JavaScript to read via the dataset property, without polluting class names or needing separate lookups.
Example
<button data-user-id="42" data-role="admin">Edit</button>
<script>
const btn = document.querySelector('button');
console.log(btn.dataset.userId); // '42'
</script>