Cannot redeclare block-scoped variable 'name'

[rajinder-yadav]

• VSCode Version: Code 1.10.2 (8076a19, 2017-03-08T14:00:46.854Z)
• OS Version: Linux x64 4.4.0-66-generic
• Extensions:

Extension	Author	Version
vscode-markdownlint	DavidAnson	0.7.0
EditorConfig	EditorConfig	0.6.0
sort-lines	Tyriar	1.2.0
vscode-eslint	dbaeumer	1.2.7
tslint	eg2	0.8.1
cpptools	ms-vscode	0.10.3
Spell	seanmcbreen	0.9.1

Below code is generating a false error:

---

Steps to Reproduce:

const sub = {
  "name": "Rajinder Yadav",
  "email": "devguy.ca@gmail.com" 
};

let t = `
{
  "name": "++lib-name++",
  "version": "0.0.0",
  "description": "",
  "keywords": [],
  "main": "dist/--libraryname--.js",
  "typings": "dist/src/--libraryname--.d.ts",
  "files": [
    "dist"
  ],
  "author": "++name++ <++email++>",
  "license": "MIT",
  "engines": {
    "node": ">=6.0.0"
  },
`;


const name = "++name++";
const email = "++email++";
let s = t
.replace(name, sub.name )
.replace(email, sub.email);

console.log(s);

Error

node_modules/typescript/lib/lib.d.ts(18935,15): error TS2451: Cannot redeclare block-scoped variable 'name'.                       
src/main.ts(25,7): error TS2451: Cannot redeclare block-scoped variable 'name'.                                                    

npm ERR! Linux 4.4.0-66-generic
npm ERR! argv "/home/yadav/.nvm/versions/node/v7.5.0/bin/node" "/home/yadav/.nvm/versions/node/v7.5.0/lib/node_modules/npm/bin/npm-cli.js" "run" "--@tscli/demo:doc_folder=docs/typedoc" "--@tscli/demo:main=build/main.js" "tsc"
npm ERR! node v7.5.0
npm ERR! npm  v4.3.0
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! @tscli/demo@0.1.0 tsc: `tsc`
npm ERR! Exit status 2
****

[rajinder-yadav]

In fact the same error can be produced with a file containing only the following line.

const name = "test";

[mjbvz]

Thanks @rajinder-yadav

I believe this behavior is by design. By default, TypeScript uses the DOM typings for the global execution environment and there is a name property on the global window in the DOM. In this case, TypeScript is providing a potentially helpful error message, provided the script is executed in a browser at least.

There are two easy ways to avoid this problem:

• Use modules. If the file is treated as a module, this error does not occur. There's a separate issue tracking allowing any file to be treated as an isolated module: Configuration For Treating JS/TS Files as Independent Units (modules) TypeScript#14279
• Don't include DOM typings. To do this, add an explicit lib property in your tsconfig.json that does not include dom:

  {
      "compilerOptions": {
          "lib": [
              "es2015"
          ]
      }
  }

Let me know if you run into any trouble with this

[dziamid]

Wow, I'm so surprised to see that typescript behaves this way. Shouldn't it suppose to act similar to nodejs where each file is a module and all variables declared in a file are locally scoped unless explicitly exported?

[mjbvz]

@dziamid TS supports both use cases. If you use import or export or module then vars are locally scoped to the file but we still allow people to use globals in older style code

[dziamid]

What about require? Does it also mean that file is a module?

[piq9117]

I added "lib": ["es2015"] in my compilerOptions and the warning is still persisting. 😢
update:
this solved it! 😃
https://stackoverflow.com/questions/40900791/cannot-redeclare-block-scoped-variable-in-unrelated-files