Created: 2014-05-19 05:26
Updated: 2019-02-28 10:06
License: mit

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Sourcemap Loader

Extracts source maps from existing source files (from their sourceMappingURL).


npm i -D source-map-loader


Documentation: Using loaders

Example webpack config

module.exports = {
  module: {
    rules: [
        test: /\.js$/,
        use: ["source-map-loader"],
        enforce: "pre"

source-map-loader extracts existing source maps from all JavaScript entries. This includes both inline source maps as well as those linked via URL. All source map data is passed to webpack for processing as per a chosen source map style specified by the devtool option in webpack.config.js.

This loader is especially useful when using 3rd-party libraries having their own source maps. If not extracted and processed into the source map of the webpack bundle, browsers may misinterpret source map data. source-map-loader allows webpack to maintain source map data continuity across libraries so ease of debugging is preserved.

source-map-loader will extract from any JavaScript file, including those in the node_modules directory. Be mindful in setting include and exclude rule conditions to maximize bundling performance.


Juho Vepsäläinen

Joshua Wiens

Kees Kluskens

Sean Larkin
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