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Conflict between package-level and module-level side-effect signals Rollup 4.x treats "sideEffects": false in package.json as a strong signal to eliminate unused exports, yet individual modules may contain top-level statements (such as console.log or mutation of global state) that are not annotated with /* @__PURE__ */ . The bundler must decide whether to tr
The goal is to select a core-js import strategy for a reusable library that polyfills ECMAScript features without mutating global built-ins or conflicting with other dependencies. Importing bare core-js mutates Array.prototype , Promise , and other globals, which can mask missing native support and collide with other polyfills. core-js-pure avoids global mut
When bundling a JavaScript library using Rollup, the effectiveness of dead-code elimination depends heavily on the sideEffects property within the package.json . While Rollup performs static analysis on ES modules to identify unused exports, the presence of global mutations or imported CSS can cause the bundler to retain unnecessary code. The uncertainty ari
Integration Goal To incorporate core-js polyfills into a modern JavaScript application without using production credentials, while maintaining bundle size and avoiding unintended prototype modifications. Constraints & Uncertainty Core-js offers a single es bundle that patches all standard prototypes, and it also provides individual module imports (e.g.,
Context A Chart.js v3 configuration that renders correctly when loaded via a full UMD bundle in development can fail after a production build with tree-shaking enabled. The ES module entry point does not automatically export or register controllers, elements, scales, or plugins; each must be explicitly imported and registered with Chart.register() . Bundlers
Goal Minimize the amount of data transferred for a single page that receives a small number of visits per month. Constraints & Uncertainty Rollup removes unused ES module exports by default, but the extent of size reduction depends on side‑effect annotations and the presence of dynamic imports. Manual chunks can split the bundle into route‑specific piece
Interoperability gap Rollup's treeshake.moduleSideEffects defaults to 'no-external' , treating external dependencies as side-effect-free unless a package declares sideEffects: false or an array in its package.json . Local development servers (Vite, webpack dev middleware) frequently disable aggressive tree-shaking to preserve HMR, which masks side-effect bug
Goal is to configure a Rollup library build that maximizes downstream tree-shaking while keeping the declared public API intact. Static tree-shaking relies on ES module syntax and accurate sideEffects metadata, and code splitting is driven by dynamic import() with manualChunks shaping. Output format choice between es and cjs changes interop helpers and expor
This build configures Rollup to tree-shake an ES-module bundle for a low-traffic site. The goal is to confirm that unused exports are removed based on side-effect analysis, and to understand whether retained code is expected behavior or a configuration gap. Rollup documentation indicates tree-shaking depends on accurate side-effect detection for imported fil
corejs
rollup
javascript
webpack
chartjs
vite