Why is my ES6 module not being tree-shaken properly during the build process?

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Why is my ES6 module not being tree-shaken properly during the build process?

Asked on Jan 14, 2026

Answer

Tree shaking is a process used to eliminate dead code from your JavaScript bundles. If your ES6 module isn't being tree-shaken properly, it might be due to how the code is structured or how the build tool is configured. Here's a simple example of how to ensure your modules are tree-shakeable:

<!-- BEGIN COPY / PASTE -->
        // utils.js
        export const usefulFunction = () => {
            console.log("This is a useful function");
        };

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

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

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

Additional Comment:

Ensure you are using ES6 "import" and "export" syntax, as tree shaking relies on static analysis of these statements.
Confirm that your build tool (e.g., Webpack, Rollup) is configured to support tree shaking. For Webpack, ensure the "mode" is set to "production".
Avoid using dynamic imports or CommonJS syntax, as they can interfere with tree shaking.
Check if any plugins or configurations in your build process are preventing tree shaking.

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Why is my ES6 module not being tree-shaken properly during the build process?

Asked on Jan 14, 2026

Answer

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