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Explicit Compile Hints with Magic Comments

Category

JavaScript

Type

New or changed feature

Status

Origin trial (Chrome Origin trial)

Intent stage

None

• Breaking change: No
• Enterprise impact: None
• Spec maturity: Incubation
• Web Platform Tests: No

WPT details: The feature doesn't trigger any functional changes and cannot be tested by WPT.

Summary

Allow attaching information about which functions should be eager parsed & compiled in JavaScript files. The information will be encoded as magic comments. We'll first target launching the file-based explicit compile hints, and as a follow up, investigate selecting individual functions for eager compilation.

Standards & signals

• Specification: https://wicg.github.io/explicit-javascript-compile-hints-file-based
• Firefox: N/A
• Safari: N/A
• Web developers: Positive — Positive signals from partners who want to use compile hints to eager-compile core JS files.
• Tracking bug: https://bugs.chromium.org/p/v8/issues/detail?id=13917

Ecosystem

• Web Platform Tests: https://wpt.fyi/results/?q=explicit-compile-hints-with-magic-comments
• Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
• GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
• chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+Explicit%20Compile%20Hints%20with%20Magic%20Comments
• MDN Web Docs: https://developer.mozilla.org/en-US/search?q=Explicit%20Compile%20Hints%20with%20Magic%20Comments
• Baseline status: https://webstatus.dev/?q=Explicit%20Compile%20Hints%20with%20Magic%20Comments

Explainers: https://github.com/WICG/explicit-javascript-compile-hints-file-based

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