lint-staged: what the purpose of 'git add' command

Question

Recently I started to introduce lint-staged into my Frontend build tool chain. And when I checked the document about it, I always find it works as following:

"husky": {
    "hooks": {
      "pre-commit": "lint-staged"
    },
"lint-staged": {
    "src/**/*.{js,jsx,ts,tsx,json,css}": [
      "prettier --write",
      "eslint --fix src/",
      "tslint --fix --project .",
      "git add"
    ]
  },

and you can find more similar usage in the link: https://github.com/okonet/lint-staged

My confusing point is the last command git add, what's the purpose of that?

My understand is lint-staged only validate the code in staged area after git add and before git commit. So can't understand why we need to add one more git add again.

Answer 1

You don't need git add since lint-staged 10

From v10.0.0 onwards any new modifications to originally staged files will be automatically added to the commit. If your task previously contained a git add step, please remove this. The automatic behaviour ensures there are less race-conditions, since trying to run multiple git operations at the same time usually results in an error.

Source: https://github.com/okonet/lint-staged#v10