rollup-plugin-dce

Usage

Install the package from npm:

$ npm install --save-dev rollup rollup-plugin-dce

Add it to your rollup.config.js:

import dce from "rollup-plugin-dce";

const config = [
  {
    input: "./src/index.ts",
    output: [{ file: "dist/my-library.js", format: "cjs" }, { file: "dist/my-library.mjs", format: "es" }],

    plugins: [
      ts(),
      dce({
        sourceGlob: "./src/**/*.ts",
      }),
    ],
  },
];

export default config;

TypeScript support

For TypeScript projects, this plugin integrates with rollup-plugin-dts and can report dead non-emit items, such as interface and type declarations.

As this requires two passes, one for the transpiled .js code, and another for the type definitions of .d.ts files, using this plugin as part of a rollup.config can lead to false positives.

For this reason, it is recommended to programmatically analyze a TypeScript project like so:

import { analyzeTSProject } from "rollup-plugin-dce";

const { files: filesWithDeadCode } = await analyzeTSProject({
  input: "./src/index.ts",
  sourceGlob: "./src/**/*.ts",
});