parserOptions inside.eslintrc.js 中的 'project' 的作用是什么？

Question

first of all, I'm very weak talk to English. sorry:(

I use ESLint in VSCode, and studying Nest.js. I can't understand 'project' option in parserOptions inside '.eslintrc.js'

    parser: '@typescript-eslint/parser',
    parserOptions: {
        project: 'tsconfig.json', // This is what I'm curious about.
        tsconfigRootDir: __dirname,
        sourceType: 'module',
    },

Why different 'parser' and 'parserOptions.project'??

Answer 1

By specifying the parser option, you're telling the compiler to use the package which it should use to parse your typescript code. Whenever you're compiling your code (or the VSCode is doing the compilation), if you've specified some parserOptions it will look into those options while building the AST out of the typescript source code.

The project option inside the parserOptions tells the parser to find and use the tsconfig.json in your project. Quoting the doc:

This setting is required if you want to use rules which require type information.

Specifying tsconfig.json and enabling/disabling various options that it provides, you can do a lot of things during typescript compilation. More about tsoconfig.jsonhere .

More reading references.

• typescript eslint parserOptions.project

• eslint specifying parser options