Lint-staged: How to set environment variable to lint-staged task

[oliverzy]

Let me say I have the following lint-staged configuration.
"lint-staged": { "*.{css,scss}": [ "prettier --fix", "git add" ], "*.{js,vue}": [ "eslint --fix --ext js,vue", "jest --findRelatedTests", "git add" ] },

But, I would like to set extra environment variable for "jest" task.
I would like to set the task as NODE_ENV=production BABEL_ENV=node jest --findRelatedTests.

Right now lint-staged will report error that NODE_ENV is not a command.

[sudo-suhas]

You can setup the environment variables for the lint-staged command itself. Here's a convoluted demo to pass a environment variable to the command which will be called by lint-staged:

package.json:

{
  "name": "test-lint-staged-env-var",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "checkmyvar": "node index.js", // The script to be called by `lint-staged`
    "precommit": "cross-env MYVAR=hello lint-staged --debug"
  },
  "keywords": [],
  "lint-staged": {
    "*": "checkmyvar"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "cross-env": "^5.1.1",
    "husky": "^0.14.3",
    "lint-staged": "^6.0.0"
  }
}

index.js:

'use strict';

if (process.env.MYVAR === undefined) {
    throw new Error('environment variable was not set!')
}

output

λ node .
E:\Projects\experiments\test-lint-staged-env-var\index.js:4
    throw new Error('environment variable was not set!')
    ^

Error: environment variable was not set!
    at Object.<anonymous> (E:\Projects\experiments\test-lint-staged-env-var\index.js:4:11)

λ yarn run precommit
yarn run v1.3.2
warning ..\package.json: No license field
$ cross-env MYVAR=hello lint-staged --debug
  lint-staged:bin Running `[email protected]` +0ms
  lint-staged Loading config using `cosmiconfig` +0ms
  lint-staged Successfully loaded config from `E:\Projects\experiments\test-lint-staged-env-var\package.json`:
  lint-staged { '*': 'checkmyvar' } +5ms
  lint-staged:cfg Normalizing config +0ms
  lint-staged:cfg Validating config +4ms
Running lint-staged with the following config:
{
  linters: {
    '*': 'checkmyvar'
  },
  concurrent: true,
  chunkSize: 9007199254740991,
  globOptions: {
    matchBase: true,
    dot: true
  },
  subTaskConcurrency: 1,
  renderer: 'verbose'
}
  lint-staged Loaded scripts from package.json:
  lint-staged { checkmyvar: 'node index.js',
  lint-staged   precommit: 'cross-env MYVAR=hello lint-staged --debug' } +18ms
  lint-staged:run Running all linter scripts +0ms
  lint-staged:run Resolved git directory to be `E:\Projects\experiments\test-lint-staged-env-var` +2ms
  lint-staged:run Loaded list of staged files in git:
  lint-staged:run [ 'yarn.lock', 'package.json', '.gitignore' ] +265ms
  lint-staged:gen-tasks Generating linter tasks +0ms
  lint-staged:cfg Normalizing config +284ms
  lint-staged:gen-tasks Generated task:
  lint-staged:gen-tasks { pattern: '*',
  lint-staged:gen-tasks   commands: 'checkmyvar',
  lint-staged:gen-tasks   fileList:
  lint-staged:gen-tasks    [ 'E:\\Projects\\experiments\\test-lint-staged-env-var\\yarn.lock',
  lint-staged:gen-tasks      'E:\\Projects\\experiments\\test-lint-staged-env-var\\package.json',
  lint-staged:gen-tasks      'E:\\Projects\\experiments\\test-lint-staged-env-var\\.gitignore' ] } +5ms
Running tasks for * [started]
  lint-staged:run-script Running script with commands 'checkmyvar' +0ms
  lint-staged:cfg Normalizing config +13ms
checkmyvar [started]
  lint-staged:find-bin Resolving binary for command `checkmyvar` +0ms
  lint-staged:find-bin `checkmyvar` resolved to npm script - `node index.js` +1ms
  lint-staged:run-script bin: npm +7ms
  lint-staged:run-script args: [ 'run',
  lint-staged:run-script   'checkmyvar',
  lint-staged:run-script   '--',
  lint-staged:run-script   'E:\\Projects\\experiments\\test-lint-staged-env-var\\yarn.lock',
  lint-staged:run-script   'E:\\Projects\\experiments\\test-lint-staged-env-var\\package.json',
  lint-staged:run-script   'E:\\Projects\\experiments\\test-lint-staged-env-var\\.gitignore' ] +1ms
  lint-staged:run-script opts: {} +3ms
checkmyvar [completed]
Running tasks for * [completed]
  lint-staged linters were executed successfully! +2s
Done in 3.00s.
[~~Executed successfully~~]

Note that I am calling a npm script to be able to verify the env var. This should work even if you are invoking any installed binaries.

[sudo-suhas]

Another solution would be to define a custom npm script which includes the environement variables:

{
  "...": "...",
  "scripts": {
    "checkmyvar": "cross-env MYVAR=hello node index.js",
    "precommit": "lint-staged"
  },
  "lint-staged": {
    "*": "checkmyvar"
  },
}

[oliverzy]

Thanks, The Solution 2 is great. I think this issue can be closed.

[okonet]

@oliverzy I see a documentation PR opportunity here.