ESLint v9 (2025-04) 사용법

ESLint 9 사용법
     - VS code 에서 ESLint 적용

 

https://eslint.org/
https://github.com/eslint/eslint

* eslint 최신 버전 설치와 설정
npm init @eslint/config@latest

    - 글로벌 설치는 권장되지 않음


* VScode extension 설치
https://marketplace.visualstudio.com/items?itemName=dbaeumer.vscode-eslint
https://github.com/Microsoft/vscode-eslint

 

eslint 로 검색 -> 제작자가 Microsoft인것 선택


* ESLint 9 에서 달라진 것

https://eslint.org/docs/latest/use/migrate-to-9.0.0
설정파일 변경 : .eslintignore , .eslintrc.js 파일 사용안함( 삭제 필요)
설정파일은 eslint.config.js 로 설정

-------------------------------------------------------------------------------
* eslint.config.js 파일 설정 예제

import js from "@eslint/js";
import globals from "globals";
import tseslint from "typescript-eslint";
import { defineConfig } from "eslint/config";

export default defineConfig([
    js.configs.recommended,
    ...tseslint.configs.recommended,
    {
        files: ["**/*.{js,ts,mjs,cjs}"],
        ignores: ["/node_modules/**"],
        languageOptions: {
            globals: {
                ...globals.browser,
                $: "readonly",               
            },
        },
        rules: {
            "no-undef": "off",
            '@typescript-eslint/no-unused-vars': 'off',
            'no-unused-vars': 'off',
            "no-debugger": "off",
            "no-unreachable": "off",
            "no-useless-escape": "off",
            "no-extra-semi": "off",
            "no-empty": "off",
            "no-extra-boolean-cast": 0,
            "plugin:you-dont-need-lodash-underscore/compatible": "off",
            "no-irregular-whitespace": "off",
            "no-prototype-builtins": "off",
            "@typescript-eslint/no-unused-expressions": "off",
            "no-control-regex": "off",
        },
    },
]);

-------------------------------------------------------------------------------
* 틀린 문법 테스트

// eslint 에러 테스트
let foo = 10
if (foo = 5) {
    console.log("Oops!")
}