Tag: TypeScript

How to migrate Javascript webpack configuration to Typescript

It turned out that the newest versions (at least 5+) of webpack support Typescript out of the box. So the algorithm is next:

  • Create tsconfig.json at the root level. Content:
    {
      "compilerOptions": {
        "module": "CommonJS",
        "target": "ES5",
        "esModuleInterop": true,
        "checkJs": false,
        "strict": true,
      }
    }
    
  • Rename all *.js files to *.ts
  • Type all of them:
    • no more ugly require, use import.
    • webpack package has typings out of the box.
      • You may find these types useful: ConfigurationRuleSetRule
      • To enable devServer write this: 
        interface Configuration extends WebpackConfiguration {
          devServer?: WebpackDevServerConfiguration;
        }
        
    • Some of the popular plugins have types too.
    • Some of them don’t have types at all:
      • Create a *.d.ts file
      • Put there something like this:
        declare module 'postcss-assets' {
          export default function postcssAssets(opts: {
            basePath: string;
            relative: boolean;
          }): unknown;
        }
        
  • Make sure your webpack.config.ts file is placed at the root level. I mean exactly at the same spot where node_modules is. Otherwise, you won’t be able to build it. No compilerOptions helped me. 
  • Run webpack. It should work.