VS Code Property 'toString' does not exist on type 'number'

Question

I hate asking this question, I imagine it is a very simple setting or typings thing that this fresh project is missing. The fact that it will run (via ts-node) tells me it is just VS Code complaining (but, why?) Google and SO searches turned up nothing concrete yet.

Visual Studio Code
Version 1.22.2
Commit 3aeede733d9a3098f7b4bdc1f66b63b0f48c1ef9
Date 2018-04-12T16:38:45.278Z
Shell 1.7.12
Renderer 58.0.3029.110
Node 7.9.0
Architecture x64

> node -v
v9.10.0

> npm -v
5.6.0

> tsc -v
Version 2.8.3

> npm ls --depth=0
api-auth-test@1.0.0 C:\...
+-- @types/node@9.6.6
+-- axios@0.18.0
`-- typescript@2.8.3

> npm ls --depth=0 -g
C:\Users\...\AppData\Roaming\npm
+-- generator@1.0.1
+-- generator-gitignore@0.1.2
+-- npx@10.2.0
+-- ts-node@6.0.1
+-- tslint@5.9.1
+-- typescript@2.8.3
`-- yo@2.0.2

I found mention here of the tsdk setting in preferences, settings, and I ensured that typescript is installed into the local node_modules

"typescript.tsdk": "node_modules\\typescript\\lib\\",

Editing this, and the error disappears briefly, then returns (as VS refreshing its cache I imagine.)

tsconfig.json

{
  "compilerOptions": {
    "target": "esnext",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "lib": [ ],                               /* Specify library files to be included in the compilation. */
    "sourceMap": true,                        /* Generates corresponding '.map' file. */
    "strict": true,                           /* Enable all strict type-checking options. */
    "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
  }
}

package.json

{
  "name": "api-auth-test",
  "version": "1.0.0",
  "description": "",
  "main": "app.ts",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@types/node": "^9.6.6",
    "axios": "~0.18.0",
    "typescript": "^2.8.3"
  },
  "devDependencies": {}
}

score 1 · Accepted Answer · answered Apr 26 '18 at 11:47

1

Your tsconfig lib is missing the es2015 entry or rather is empty.

"lib": [
    "dom",
    "es2015"
],

Removing es2015 gave me the error you are facing. For information on --lib option see What does the tsconfig option "lib" do?

answered Apr 26 '18 at 11:47

Suraj Rao

29,388
11
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103

How utterly maddening, I tried about every permutation of options for lib (including "dom" **and** "es6"), but the error wouldn't go away. I did as you suggested, **boom** problem solved! A million thanks for the fix and especially the link. I haven't seen it mentioned specifically but, am I to understand they are not "additive"? Should adding just "es6" gave **not** been sufficient? Or is "dom" the more critical piece for this specific `toString` issue? – t.j. Apr 26 '18 at 22:17
1

"dom" is the runtime environment you target. It has its own set pf api. Maybe https://basarat.gitbooks.io/typescript/docs/types/lib.d.ts.html will help – Suraj Rao Apr 27 '18 at 04:52
Ha, indeed! "This code type checks fine because the toString function is defined in lib.d.ts for all JavaScript objects.", and then the very error I was looking for. EXCELLENT find! – t.j. Apr 27 '18 at 06:14

score 0 · Answer 2 · answered Aug 06 '19 at 15:28

I have observed similar issues with Angular 8 based solutions.These are set up with "es2018", after adding also "es2015" the red squigglies went away.

   {
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/out-tsc",
    "sourceMap": true,
    "declaration": false,
    "module": "es2015",
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2018",
      "es2015",
      "dom"
    ]
  }
}

Now, it might be the case that you should not mix these libs and just stick to one of these. But the point was to underline that Angular 8 uses "es2018" and I observed that adding "es2015" also fixed up some seemingly wrong errors that were fine when running inside the browser (false positives).

VS Code Property 'toString' does not exist on type 'number'

2 Answers2