TypeScript 不会推断 CommonJS 导入的类型（通过 require()）

Question

• My code runs in Node.js environment. I have installed @types/node . When I write import http = require('http') or import * as http from 'http' , the type of the object I'm importing is inferred:
• However, when I write const fs = require('fs'); , the type is any . Why is that? Can I do anything about it?

Answer 1

TL;DR

A possible fix for this is to import the types for Node.js.

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Full Solution

The solution for this issue is to import the types for Node.js.

This is available as an npm package . It contains all of the types for Node.js.

To install it, you need to run the following command.

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

The reason the --save-dev flag is on the install command is because it isn't supposed to be a dependency, but instead a dev (development) dependency. This will not install this package if, for example, your project is installed as an npm module.

After this, IntelliSense will automatically pick up the type definitions, and will add auto-correct your Node.js code, including doing some other handy things.

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If the type definitions don't get picked up, then the best solution is to restart Visual Studio Code. If that doesn't work, make sure that this is in your package.json file.

{
  "devDependencies": {
    "@types/node": "^17.0.31"
  }
}

Note: The version was correct at the time of post.

If it isn't, then add that code in your package.json file, save it, and run the following command.

$ npm install

This should install it successfully.