Cannot find namespace 'NodeJS'.

If you also have tsconfig.app.json in your working directory, try to add the attribute node to the types field. Like: { "extends": "../tsconfig.json", "compilerOptions": { "outDir": "../out-tsc/app", "module": "es6", "baseUrl": "", "types": ["node"] --> ADD THIS }, "exclude": [ "test.ts", "**/*.spec.ts" ] }

This was working for me…

For me "types": ["node"] didn’t work, but it worked by adding this directive:

{
  "compilerOptions":
  {
    ...
    "typeRoots": [
      "node_modules/@types"
    ]
  }
}

PS: I’m in an ionic 3 project running on Windows.