TypeScript: Duplicate identifier 'IteratorResult'

Question

I\'m trying to compile via tsc--which I\'ve installed globally--and I\'m getting an error:

~/AppData/R         


        

Answer 1

For me it turned out I had a node_modules folder in a parent directory project, something similar to this:

node_modules
my-project
- node_modules

Since the node_modules had an older version of @types/node installed, the problem happened. In my case the solution however wasn't to update @types/node but instead to remove those node_modules since I wasn't using them in the first place.

If you actually need to have a node_modules in a parent directory with different types and this is how you want it to be, then you can specify the typeRoots specifically:

{
  "compilerOptions": {
    "module": "esnext",
    "target": "es6",
    "declaration": true,
    "outDir": "./dist",
    "typeRoots": ["./node_modules/@types/"]
  },
  "include": [
    "src/**/*"
  ]
}

That way, the parent node_modules aren't scanned for types. Otherwise they are, read here: https://www.typescriptlang.org/docs/handbook/tsconfig-json.html#types-typeroots-and-types

By default all visible “@types” packages are included in your compilation. Packages in node_modules/@types of any enclosing folder are considered visible; specifically, that means packages within ./node_modules/@types/, ../node_modules/@types/, ../../node_modules/@types/, and so on.