Limited supportUseful when the module graph includes typed assets such as JSON or CSS and you want import intent to stay explicit.
Modules Limited support

Import assertions

Import assertions attach explicit type metadata to module imports. They help runtimes and tooling interpret non-JavaScript modules more safely and predictably.

ModulesImportsMetadata

Overview

Import assertions attach explicit type metadata to module imports. They help runtimes and tooling interpret non-JavaScript modules more safely and predictably.

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
javascript.statements.import.import_assertions
Deprecated Non-standard
91
91
91
Statement
import assertions.type css
Deprecated Non-standard

`assert {type: 'css'}`
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93
import assertions.type json
Deprecated Non-standard

`assert {type: 'json'}`
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91
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)
Notes 1 item(s)
Removed
  • This feature was removed in a later browser version (126)

Syntax

JAVASCRIPT 
import data from './data.json' with { type: 'json' };
import styles from './styles.css' with { type: 'css' };

Use cases

  • Typed JSON imports

    Mark imported data as JSON so the loader knows exactly how it should be interpreted.

  • Safer module boundaries

    Keep asset imports self-describing in larger codebases with multiple module types.

Cautions

  • Support and syntax have evolved, so match the import form to the runtimes and bundlers you actually target.
  • Typed imports improve clarity, but they do not replace validation of untrusted data.

Accessibility

  • No direct accessibility effect, though clearer module boundaries can reduce implementation mistakes in user-facing content.
  • If imported assets include labels or messages, preserve their localization and accessibility review path.

Related links

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