Define our own in-repo babel configuration #8624
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This commit is a non-breaking change. There are slight differences with how class properties are initialised - it removes setting them to undefined before reassigning them, which isn't needed.
Now we transpile based upon our browserslist, we don't force the usage of these transpilations. In practice, given our current browserslist config this means that the following transforms are now no longer ran (for instance our compiled output now contains `foo?.bar` instead of that being transformed): - proposal-numeric-separator - proposal-nullish-coalescing-operator - proposal-optional-chaining
alex-page
approved these changes
Mar 10, 2023
alex-page
reviewed
Mar 10, 2023
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| '@shopify/polaris': major | ||
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| No longer transpile optional chaining, nullish coalescing or numeric separators, as our target browser environments all have native support for these syntaxes. This removes support for apps using webpack4, which unable to parse these syntaxes. |
alex-page
approved these changes
Mar 10, 2023
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WHY are these changes introduced?
This PR replaces using
@shopify/babel-presetwith using the underlying presets directly.As part of this we simplify the plugins we use and lean more heavily on
@babel/preset-env. As a result of this we no longer transpile numeric separators (1_000), nullish coalescing operators (foo ?? 'bar') and optional chainingfoo?.barbecause our browserslist targets say that those features are all supported in the browsers that we target.This means that our build output now contains optional chaining et al.
A breaking change side-effect of this is that code that uses these features will no longer successfully parse in webpack4, as webpack4 uses an old version of acorn does not understand these syntaxes. Webpack5 uses a newer version of acorn that can read this just fine.
WHAT is this pull request doing?
Replace
@shopify/babel-configwith using@babel/preset-env,@babel/preset-typescriptand@babel/preset-reactdirectly.This PR is split into two commits. The first replaces
@shopify/babel-presetwith inline config, with minimal changes. The second removes the forced compilation of the 5 plugins that were always forced to be enabled.How to 🎩
~/projects/polarisdirectory and runcd package,yarn,yarn run turbo run build --filter='!polaris.shopify.com' --forceto produce a clean build~/src/github.com/Shopify/polarisdirectory and runcd package,yarn,yarn run turbo run build --filter='!polaris.shopify.com' --forceto produce a buildtouch out.txt; for PACKAGENAME in $(ls -1 . | grep '^polaris-'); diff -ru ~/projects/polaris/$PACKAGENAME $PACKAGENAME -x '*.tsbuildinfo' -x '*.d.ts.map' -x'.turbo' -x '*.esnext' >> out.txtto compare the build folder output. Note that the differences are as follows:void 0. In all cases either the value is already implicitly undefined, or is assigned to a value shortly afterwards