Typescript/NPM - How to build both ESM and CJS in project. @see https://www.sensedeep.com/blog/posts/2021/how-to-create-single-source-npm-module.html

build.sh

tsc -p tsconfig.json && tsc -p tsconfig-cjs.json

tsconfig-cjs.json

{
    "extends": "./tsconfig-base.json",
    "compilerOptions": {
        "module": "commonjs",
        "outDir": "dist/cjs",
        "target": "es2015"
    }
}

tsconfig-esm.json

{
    "extends": "./tsconfig-base.json",
    "compilerOptions": {
        "module": "esnext",
        "outDir": "dist/mjs",
        "target": "esnext"
    }
}