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How to find module "fs" in VS Code with TypeScript?

I'm running on a MacBook Air. I installed VS Code as an IDE and also have TypeScript installed.

I have a simple file with just this line:

import fs = require('fs');

I'm getting a red squiggly under the 'fs' inside the parenthesis and the error message is [ts] Cannot find module 'fs'. The file has a .ts extension. I'm new to JavaScript and to TypeScript, but I was under the impression that fs was a core module, so how could it not be found? How do I fix the problem?

Other things that I tried already:

Putting a simple function body in the file and then compiling on the command line with tsc. I get an essentially equivalent error there: error TS2307: Cannot find module 'fs'.

On the command line sudo npm install fs -g. This reports apparent success, but doesn't fix the problem.

I poked around SE and the web, but the answers that seemed close all appear to assume that 'fs' is available.

You're definitely executing this code with node?
The plan is to execute it with node, yes. Local file access is ok for the current application. @peteb

D
David Sherret

You need to include the definition file for node.

TypeScript 2.0+

Install using npm:

npm install --save-dev @types/node

TypeScript < 2.0

If you use typings then you can run this command:

typings install dt~node --global --save

Or if you are using typings < 1.0 run:

typings install node --ambient --save

Or if all else fails, manually download the file here and include it in your project.


I used the command that you had prior to your edit, and that did the trick. (typings install node --ambient --save) Thanks!
@Brick yes that will work. The command in the answer is for typings 1.0 which was just released
With yarn: yarn add @types/node --dev
Tried it. But still didn't work for me. Any other reason for still getting Error: Can't resolve 'fs' ?
@barath did you find a solution? I also have this error.
d
dshepherd

There is a better way now without going to the previous tsd or typings tools. NPM now has the @types package for typescript. In this example you need the package @types/node:

npm install "@types/node" --save-dev

Make sure you are using the save-dev option to only install the types in development mode, not in production. You should have the latest node libraries when use the npm install "@types/" syntax...

It not finding the fs package because the previous tools typings most likely not using the latest node.d.ts definition file.

Your tsconfig.json file needs to be updated to find these type packages. My example if using jquery, jqueryui and node types. Assuming you need the syntax to work for your code editor as well, in this case the 'atom' code editor

{
"compileOnSave": false,
"compilerOptions": {
    "rootDir": "src",
    "sourceMap": true,
    "target": "es5",
    "module": "amd",
    "declaration": false,
    "noImplicitAny": false,
    "removeComments": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "moduleResolution": "node",
    "lib": ["es2015", "dom"],
    "baseUrl": "./",
    "typeRoots": [
        "node_modules/@types"
    ],
    "types": [
        "jquery",
        "jqueryui",
        "node"
    ],
    "paths": {
        "src/*": ["src/*"]
    }
},
"exclude": [
    "node_modules",
    "dist",
    "build"
],
"filesGlob": [
    "./src/**/*.ts",
    "./test/**/*.ts",
    "./typings/index.d.ts",
    "./custom_typings/**/*.d.ts",
    "./node_modules/@types/**/*.d.ts"
],
"atom": {
    "rewriteTsconfig": false
}
}

E
Eric N

"fs" is a core Node module and I think your import statement syntax is a little off. Try:

import * as fs from "fs";

Ah the typings for Node isn't included. Try adding this file and a reference path to it: github.com/DefinitelyTyped/DefinitelyTyped/blob/master/node/…
@EricN The page leads to a 404. Typings are needed even if the module is part of the whole NodeJs core ?
Yeah the typing is necessary. Node isn't written in Typescript so it doesn't have any of the type data that Typescript looks for. The definition file provides all that type data for you.
B
Brick

All you need is "moduleResolution" set to "node" in your tsconfig.json:

{
  "compilerOptions": {
      ...
      "moduleResolution": "node"
      ...
  }
}

execute

npm install @types/node --save-dev

and now you can use standard TypeScript import:

import * as fs from "fs";

Tried but still getting same problem
@pardeepjain, any chance you have old typescript? Using vscode? Check Typescript version on the status bar.
I only needed the first part of this - I have a tiny script which doesn't need a packages.json file
U
User Rebo

You have three options in tsconfig.json (here: Node 11+), see docs:

Either specifiy both typeRoots and types, only typeRoots or remove both lines completely (recommended):

{"compilerOptions": {
  ...
  "typeRoots": ["node_modules/@types"],  // "typeRoots": [] -> won't work
  "types": ["node"]                      // "types": [] -> won't work
}}

Install types:

npm install --save-dev @types/node

Use promise based file system (e.g to use async / await):

import {promises as fs} from 'fs';

async function foo() {
    ...
    await fs.writeFile('./yourPath', 'YourContent');
}

When I created a declarations folder to put my .d.ts files in and created a typeRoots array in my compilerOptions I had not specified the node_modules/@types and that's what caused the error for me. Once I added that to the typeRoots array, it worked again.
Excellent answer. Unlike 90% of folks here, I already had node types installed but was running into the issue where core node modules (like os where not being found at runtime)
M
Madhu Ranjan

Typescript knows about modules based upon conventions , check Module resolution for more detail.

Also for IDE to know about fs module, you have to provide typings for node.

Also check this github issue


j
jon

on my side this work

 const fs = require('fs') as typeof import('fs');

of for nwjs with vitejs

 const fs = nw.require('fs') as typeof import('fs');

this remove the any