tsconfig-esm.json

{
  "compilerOptions": {
    "module": "es2015",
    "target": "ES5",
    "sourceMap": true,
    "declaration": true,
    "experimentalDecorators": true,
    "outDir": "dist/esm",
    "moduleResolution": "node"
  },
  "files": [
    "typings/es6-shim/es6-shim.d.ts",
    "src/index.ts"
  ]
}