Commit e1f67396 authored by Jake Burden's avatar Jake Burden Committed by Amy Qualls

Add documentation about Babel polyfills

Add docs about finding polyfills in webpack report
parent 9db5eb50
...@@ -308,6 +308,8 @@ Piwik ...@@ -308,6 +308,8 @@ Piwik
PgBouncer PgBouncer
plaintext plaintext
Poedit Poedit
polyfill
polyfills
pooler pooler
PostgreSQL PostgreSQL
precompile precompile
......
...@@ -163,3 +163,33 @@ To return to the normal development mode: ...@@ -163,3 +163,33 @@ To return to the normal development mode:
1. Run `yarn clean` to remove the production assets and free some space (optional). 1. Run `yarn clean` to remove the production assets and free some space (optional).
1. Start webpack again: `gdk start webpack`. 1. Start webpack again: `gdk start webpack`.
1. Restart GDK: `gdk-restart rails-web`. 1. Restart GDK: `gdk-restart rails-web`.
### 8. Babel polyfills
> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/28837) in GitLab 12.8.
GitLab has enabled the Babel `preset-env` option
[`useBuiltIns: 'usage'`](https://babeljs.io/docs/en/babel-preset-env#usebuiltins-usage),
which adds the appropriate `core-js` polyfills once for each JavaScript feature
we're using that our target browsers don't support. You don't need to add `core-js`
polyfills manually.
NOTE: **Note:**
GitLab still manually adds non-`core-js` polyfills for extending browser features
(such as GitLab's SVG polyfill) that allow us reference SVGs by using `<use xlink:href>`.
These polyfills should be added to `app/assets/javascripts/commons/polyfills.js`.
To see what polyfills are being used:
1. Navigate to your merge request.
1. In the secondary menu below the title of the merge request, click **Pipelines**, then
click the pipeline you want to view, to display the jobs in that pipeline.
1. Click the [`compile-production-assets`](https://gitlab.com/gitlab-org/gitlab/-/jobs/641770154) job.
1. In the right-hand sidebar, scroll to **Job Artifacts**, and click **Browse**.
1. Click the **webpack-report** folder to open it, and click **index.html**.
1. In the upper left corner of the page, click the right arrow **{angle-right}**
to display the explorer.
1. In the **Search modules** field, enter `gitlab/node_modules/core-js` to see
which polyfills are being loaded and where:
![Image of webpack report](img/webpack_report_v12_8.png)
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