webextension-polyfill updates

[rebloor]

Description

These changes are designed to emphasize that the webextension-polyfill is now only needed when an extension want to target Chrome 147 or earlier.

Related issues and pull requests

Related changes to the Extension Workshop content in mozilla/extension-workshop#2401.
Fixes #44114 (with content from Issue-44114-Chrome-support-for-the-browser-namespace)

[github-actions]

Preview URLs (5 pages)

• /en-US/docs/Mozilla/Add-ons/WebExtensions/API/proxy
• /en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/executeScript
• /en-US/docs/Mozilla/Add-ons/WebExtensions/API
• /en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension
• /en-US/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations

External URLs (9)

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API
Title: JavaScript APIs

• https://crbug.com/500769389 (1 time) (Note! This may be a new URL 👀)
• https://github.com/mozilla/webextension-polyfill (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API/proxy
Title: proxy

• https://developer.chrome.com/docs/extensions/reference/api/proxy (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/executeScript
Title: tabs.executeScript()

• https://github.com/mozilla/webextension-polyfill (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension
Title: Build a cross-browser extension

• https://crbug.com/500769389 (2 times) (Note! This may be a new URL 👀)
• https://developer.chrome.com/docs/extensions/develop/concepts/browser-namespace (1 time) (Note! This may be a new URL 👀)
• https://developer.chrome.com/docs/extensions/develop/migrate (1 time) (Note! This may be a new URL 👀)
• https://extensionworkshop.com/documentation/develop/manifest-v3-migration-guide/ (1 time) (Note! This may be a new URL 👀)
• https://github.com/mozilla/webextension-polyfill/ (2 times) (Note! This may be a new URL 👀)

(comment last updated: 2026-08-23 16:39:09)

[Rob--W]

Could you update the text to account for mozilla/webextension-polyfill#942 ? There is a small subset of extensions where "148" does not apply, but "152" does.

[rebloor]

@Rob--W updated re 152

[Rob--W]

I think that this might be conflicting with some other PRs, notably #44959 and the older PR at #44149 . In the interest of avoiding duplicate/overlapping work I suggest combining 44149 with this one (this one about 152+148 supersedes the part about 148).

I already approved Oliver's PR, so we could also merge that first, merge/rebase this branch. And then do a final pass for inconsistencies. I spotted at least one inconsistency, the existing claim that devtools doesn't support Promise. That note should be adjusted to state that support was added in 152.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[github-actions]

[mdn-linter] _{reported by reviewdog 🐶}

Suggested change

[rebloor]

@Rob--W includes changes from #44149, and I've made updates, so everything should now be accurate and consistent. I'm wondering whether, when we can be reasonably assured that most new cross-browser development will target the versions supporting the browser and promises, we should review the three articles to eliminate any confusion or uncertainty about which one to consult.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[Rob--W]

@Rob--W includes changes from #44149, and I've made updates, so everything should now be accurate and consistent. I'm wondering whether, when we can be reasonably assured that most new cross-browser development will target the versions supporting the browser and promises, we should review the three articles to eliminate any confusion or uncertainty about which one to consult.

I'd like to preserve a historical reference because that would answer questions "why are there many ways to do the same and which is recommended?". If we can remove some duplication and instead link to a canonical article that would be nice, but let's not add that scope creep to this PR.

[rebloor]

Hmm. Chained copy-paste error?

[rebloor]

@Rob--W, my comment about reviewing the three articles wasn't so much about removing historical information as about making sure the current situation was as clear as possible across the API, differences, and cross-browser pages. I've made a note to myself to review and create a PR if it looks useful.

[rebloor]

@Rob--W ready for your review again