How does tree shaking in ES6 modules affect module resolution, and can it lead to missing imports in the build?

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How does tree shaking in ES6 modules affect module resolution, and can it lead to missing imports in the build?

Asked on Dec 17, 2025

Answer

Tree shaking is a technique used in JavaScript to eliminate dead code, specifically in ES6 modules, by removing unused exports during the build process. This helps optimize the final bundle size. Here's a simple example to illustrate how tree shaking works:

<!-- BEGIN COPY / PASTE -->
        // utils.js
        export function usedFunction() {
            console.log("This function is used.");
        }

        export function unusedFunction() {
            console.log("This function is not used.");
        }

        // main.js
        import { usedFunction } from './utils.js';

        usedFunction();
        <!-- END COPY / PASTE -->

Additional Comment:

Tree shaking relies on ES6 module static structure, meaning imports and exports must be statically analyzable.
If "unusedFunction" is not imported or used, it will be removed from the final bundle.
Ensure your build tool (e.g., Webpack, Rollup) is configured to support tree shaking.
Tree shaking does not cause missing imports if the code is correctly structured and all necessary imports are used.

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How does tree shaking in ES6 modules affect module resolution, and can it lead to missing imports in the build?

Asked on Dec 17, 2025

Answer

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