Read arguments from command line - error TS2304: Cannot find name 'process'

Question

Using TypeScript version 1.7.5.

I am writing a nodeJS program in which I want to read in command line arguments passed by the user (2 integers). Everything works fine in raw JavaScript, but an issue arises with TypeScript.

When

process.argv

is used in the TypeScript file, when it is compiled to JavaScript the compiler errors because it does not recognize the "process" variable.

error TS2304: Cannot find name 'process'

I have tried declaring a new var "process" at the top of the file, but that overrides the native variable and it no longer contains the arguments...

I would like to keep all my code all in TypeScript, only compiling to JavaScript at build time. What is the best workaround for this issue?

Solution 1

Update: September 2016

You need to make sure that the type definitions for Node are available. The way to do this depends on which version of TypeScript you are using.

TypeScript 1

Use Typings to install the definitions.

typings install --save --global env~node

Be sure to include typings/index.d.ts in your tsconfig.json file. Either include it in the "files" array:

"files": ["typings/index.d.ts"]

Or ensure it is omitted from the "exclude" array.

TypeScript 2

In TypeScript 2, definitions can be installed via npm under the @types scope.

npm install --save-dev @types/node

Original Answer: February 2016

You have to make sure the appropriate type definitions are available. Use the typings package manager for this. Install the definitions for node as follows:

typings install --save --ambient node

Now, there are a few ways you can make sure the definitions are available to the compiler. The preferred method is to set up your tsconfig file like so:

{
  "exclude": [
    "typings/browser.d.ts",
    "typings/browser",
    "node_modules"
  ]
}

Or, alternatively:

{
  "files": [
    "typings/main.d.ts"
  ]
}

If you are not using a tsconfig file, you can use a reference at the top of your main entry file, like so:

/// <reference path="path/to/typings/main.d.ts" />

Solution 2

This question is at top of Google results when looking for "Cannot find name 'process'", so I'll add my 2 cents to a not-too-unrelated issue here.

If you need to get rid of the error when using if(process.env.NODE_ENV === "production") to strip some code in production with webpack, just add the following declaration before the line:

declare var process: {
   env: {
       NODE_ENV: string
   }
};

Solution 3

TypeScript 2 - Windows Users

Since this question is at the top of Google for "ts2304 cannot find name 'process'" I want to add some help for Windows users. I was attempting to use environmental variables from a config file and was stuck with this error.

TSError: Unable to compile TypeScript.

Cannot find name 'process'- (2304)

I finally added this to my tsconfig.json:

{
  "compilerOptions": {
    "typeRoots": [
      "./node_modules/@types"
    ]
  }
}

This was with tsconfig.json and node_modules in the same directory level but for some reason the compiler just was not seeing it. What was strange is this error only occurred for the process.env variables as the rest of my code had no trouble compiling.

Solution 4

My complete solution for on OSX brings together some of the above for error TS2304: Cannot find name 'process'. My use case was a partially migrated React project from jsx/js to tsx/ts.

1. yarn add -D @types/node
2. Updated tsconfig.json to include "typeRoots": ["./node_modules/@types"]
3. include import { } from 'node'; at the top of the file with the error

All 3 steps were required for me when using Typescript v2.7.1

Solution 5

I ran into this issue and had to add the following to the file containing the process call:

import { } from 'node';

At which point it recognized process

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Comments

[Rohit Falor]

Thanks! All I had to do was include the last part referencing the main.d.ts file at the top of my program. It now compiles and runs as expected.

[Offirmo]

with typescript 2, its now npm i -D @types/node

[McMath]

@Offirmo Thanks for the input. I've updated the answer accordingly.

[rapasoft]

Thank you very much, this did the trick together with adding node typings via npm install --save-dev @types/node