Choosing core-js polyfills: full bundle or targeted imports
Decide between full core-js, modular feature imports, and Babel usage-based polyfills based on bundle size and target browsers.
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corejsDiagnosing core-js Array.prototype.flat polyfill inclusion in modern builds
When core-js injects Array.prototype.flat polyfill code into bundles for native‑supporting environments, bundle size grows needlessly. This diagnostic guide walks through recognizable conditions, a cause‑diagnostic table, ordered checks, fixes tied to findings, and escalation criteria.
core-js/stable global polyfills mutate native built-ins after import
Adding core-js to a bundle should provide polyfills without changing how existing native methods behave for code that does not opt in. When core-js/stable is used with Babel preset-env, third-party libraries that feature-test built-ins may see modified globals such as Promise or Array. The exact behavior depends on whether core-js/stable or core-js/pure is i
Which configuration takes precedence when both browserslist and explicit targets are defined in Babel preset-env?
Babel's preset‑env resolves the set of supported runtime environments by merging targets from a browserslist configuration and an explicit targets option. When both are present, the precedence governing which source takes effect is not specified in the documentation, creating ambiguity for build pipelines that depend on consistent polyfill injection. The res