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build(core): Compile SDK to ES2018 to drop inlined TS helpers - #6957
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Raise the TypeScript compile target from es6 to es2018 so async/await and object rest are emitted natively instead of inlining `__awaiter`/`__rest` into every file of dist/js. `lib` stays at es7 to keep runtime API usage unchanged. Jest keeps compiling at es2016 to mirror Metro's Babel preset, which downlevels async functions onto the global (polyfilled) Promise. Closes #6955 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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antonis
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October 28, 2026 10:28
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📢 Type of change
📜 Description
Raises the TypeScript compile
targetof the SDK fromes6toes2018. TypeScript then emitsasync/awaitand object rest natively, instead of pasting a copy of the__awaiter/__resthelpers into each of the 31 affected files indist/js.tsconfig.build.jsonandtsconfig.build.tools.json:targetgoes fromes6toes2018.tsconfig.lint.json: same bump, to keep it in sync.tsconfig.json, which only Jest uses: pinned totarget: "es2016", with a comment (see below).libstays ates7on purpose. It limits which runtime APIs the code can use, and Metro converts syntax but doesn't add polyfills.We don't use the issue's other suggestion (
importHelpers+tslib).importHelperswas turned off on purpose in #4573, and it would add a runtime dependency.Why Jest stays at es2016:
Sentry.initreplaces the globalPromisewith React Native's polyfill (reactnativeerrorhandlersutils.ts).__awaiterand Babel's async-to-generator helper both build promises from that global. Nativeasyncalways uses the engine's built-in promises. In apps,@react-native/babel-presetstill convertsasyncto generators (unless theunstable_preserveAsyncexperiment is on), so the runtime behavior is unchanged. Keeping Jest at es2016 matches that. With es2018, 37 tests inreactnavigation.ttid.test.tsxandprofiling/integration.test.tsfail, because they rely on fake timers flushing the polyfilled promises.Compatibility: no new syntax requirement.
@sentry/core, which every app already bundles, ships ES2020 syntax (optional chaining, nativeasync). There's no API, type, or bridge change; the API report is unchanged.Caveat: app Jest suites that don't run Babel on
@sentry/react-nativewill now get nativeasyncfrom the SDK. Tests that relied on fake timers to flush SDK async work may need an extraawait. The commonly recommendedtransformIgnorePatternswhitelist includes@sentry/react-native, so most setups aren't affected.💡 Motivation and Context
Closes #6955: every app bundle carries ~31 duplicate copies of the TS helpers.
💚 How did you test it?
yarn build(deleteddist): no__awaiter/__restleft. The only remaining helpers are__createBinding/__exportStarfrom one CommonJSexport *in the Node-only tools output; they were already there and don't reach the app bundle.yarn test: 2236 SDK + 357 tools tests pass.yarn lint,yarn circularDepCheck,yarn api-report:check: pass (API report unchanged).samples/react-native(RN 0.88,--dev false --minify true), before vs after:__awaiteroccurrences in the bundle drop from 27 to 6 (the remaining 6 come from other packages). The number of nativeasyncfunctions in the bundle is unchanged, which confirms Metro still converts the SDK'sasynccode.ready-to-mergeCI.📝 Checklist
sendDefaultPIIis enabled.🔮 Next steps
ready-to-mergelabel for the full sample/E2E CI (old/new architecture, Expo).🤖 Generated with Claude Code