This is a practical reference for tell the browser whether a script is classic javascript, a module, or data. Keep it nearby when you are writing a page, but do not worry about memorizing every entry at once.
What this reference covers
Tell the browser whether a script is classic JavaScript, a module, or data. The entries below summarize the most useful choices and what each one means.
| Value or item | What it means |
|---|---|
omitted | Classic JavaScript |
module | ES module with module loading |
importmap | Maps module import specifiers |
application/json | Inert JSON data |
speculationrules | Speculative navigation instructions |
See it in HTML
A small example shows how one of these ideas appears in a normal page:
<script type="application/json" id="page-data">
{"lesson": "HTML", "chapter": 1}
</script>How to use the reference
Begin by identifying what the page is trying to achieve. Then choose the entry that describes that job, instead of choosing a setting merely because it looks familiar.
Read the code from the outer element inward. Pay attention to attribute names, tag nesting, and any links between elements through IDs. A browser may accept some incorrect markup, but accepting it is not the same as using it correctly.
A useful check before publishing
Try changing one choice in the example while keeping the rest of the page the same. Inspect the result in your browser. For compatibility-sensitive features, test another browser; for accessibility-sensitive features, use keyboard navigation and an accessibility inspector.
Some entries describe browser hints rather than guarantees. User input still needs server-side validation, and event-based behavior needs JavaScript even if the HTML describes the control.
Common Beginner Mistakes
- Treating every item in a reference list as interchangeable instead of choosing the one that matches the job.
- Copying reference markup without checking the element’s surrounding context or required attributes.
- Assuming one successful browser test proves the markup is accessible or universally supported.
Key Takeaways
- Tell the browser whether a script is classic JavaScript, a module, or data.
- Pick a setting for its meaning, then test the smallest working example.
- HTML references are most useful when combined with validation, browser inspection, and accessibility testing.