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Question0 answers4,334 followingPosted 13 Aug 2025, 11:55 UTC117.7K views2,167 votes

@babel/preset-env: useBuiltIns 'usage' or 'entry' for bundle size

Goal: ship the smallest polyfill set for the project’s browserslist targets without duplicating core-js modules across the bundle. The application has no global polyfill entry file, but it does have a single JavaScript entry point. With @babel/preset-env 7.x and core-js 3, useBuiltIns: "usage" scans each file and emits only polyfills for APIs actually refere

Community & Careers · Editorial question

babel

Community & Careers

Question1 answer2,024 followingPosted 28 Feb 2025, 04:26 UTC103.5K views1,306 votes

owner answered

@babel/preset-env: useBuiltIns usage vs entry for serverless polyfill size

Goal: select the @babel/preset-env useBuiltIns mode that keeps polyfill payload small for a low-traffic serverless function without risking missing polyfills in production. The project uses Babel 7 and declares target environments in browserslist . Constraint: usage injects only polyfills detected as used per file, usually reducing bundle size, but it can mi

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serverless preset-env

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