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Learn how to use Core‑JS 3.x to polyfill only the features you need. This guide shows the difference between <code>pure</code> and <code>stable</code> imports, walks through a Promise polyfill example, and explains how to keep your bundle lean.
Learn how Babel’s useBuiltIns: 'usage' option adds only the polyfills your code actually uses, reducing bundle size while maintaining compatibility.
Learn how to implement Array.prototype.flat using core-js with a minimal footprint. This guide covers targeted feature imports, load-order requirements, and operational verification.
Guidance on importing only the needed polyfill, keeping globals clean, and verifying legacy support in a JavaScript library.
For an internal tool that must run on IE10, the team needs to decide how to provide CSS Grid layouts while keeping overall effort low. The options are to author a separate stylesheet using IE10’s prefixed -ms-grid properties or to load a JavaScript polyfill that translates modern display: grid syntax to the prefixed engine. The prefixed approach avoids runti
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
A project using @babel/preset-env must decide between useBuiltIns: 'usage' and useBuiltIns: 'entry' to control polyfill inclusion for browsers listed in the target configuration. The goal is to limit JavaScript payload while ensuring that runtime features required by the application's user-facing components are available across supported environments. The '
Goal Determine whether a small Node.js or bundler-based application can migrate to core-js 3.x without downtime while importing core-js/stable, or whether core-js/pure is required to avoid changing native built-in behavior. Constraints and uncertainty core-js 3.x's core-js/stable entry point patches native globals such as Promise, Array, and String at import
Goal Determine whether core-js DOM collection polyfills exhibit memory leak patterns that persist across versions, particularly when used in long-running browser applications. Constraints The investigation must focus on documented behavior rather than unverified reports. Memory leak patterns may differ between core-js 2.x and 3.x branches due to architectura
corejs
javascript
babel
nodejs