ESLint - The Essential Linter and Formatter for JavaScript and TypeSc…

…ript (#1224)

* eslint config + packages

* updated eslint config

* fix the issue eslint adding ;;;; at interfaces

* first round with eslint --fix .

* removed config for unused export

* Revert "first round with eslint --fix ."

This reverts commit 77a88e0.

* removed config for camelCase

* for real this time, first round of eslint --fix .

* halfway to manual eslint fix

* eslint done

* added "how to setup" the hook to eslint --fix each new file before commit (if wanted)

* removed eslintrc config file duplicat

* fix human error + ignore build folder + merge overrides

* added curly brace style + eslint

* applied double quote linter rule

* added lefthook

* test precommit

* test precommit

* test precommit

* test precommit

* test precommit

* test precommit

* test precommit

* github action to run eslint

* added node_modules to ignore eslint

* different action for typescript

* no need for different glob (default src)

* node 20

* node 20

* removed no longer needed install file

* remove hooks part from README

* eslint fixes

---------

Co-authored-by: Frederico Santos <frederico.f.santos@tecnico.ulisboa.pt>

.eslintignore

@@ -0,0 +1,7 @@
+dist/*
+build/*
+coverage/*
+public/*
+.github/*
+node_modules/*
+.vscode/*

.eslintrc

@@ -1,17 +1,29 @@
 {
-	"env": {
-		"browser": true,
-		"es2021": true
-	},
-	"parserOptions": {
-		"ecmaVersion": "latest",
-		"sourceType": "module"
-	},
-	"overrides": [
-		{
-			"files": ["src/**/*.ts"],
-			"extends": "eslint:recommended"
-		}
-	],
-	"rules": {}
+  "parser": "@typescript-eslint/parser", // Specifies the ESLint parser for TypeScript
+  "plugins": ["@typescript-eslint", "import"], // Includes TypeScript and import plugins
+  "overrides": [
+    {
+      "files": ["src/**/*.{ts,tsx,js,jsx}"], // Applies these rules to all TypeScript and JavaScript files in the src directory
+      "rules": {
+        // General rules that apply to all files
+        "eqeqeq": ["error", "always"], // Enforces the use of === and !== instead of == and !=
+        "indent": ["error", 2], // Enforces a 2-space indentation
+        "quotes": ["error", "double"], // Enforces the use of double quotes for strings
+        "no-var": "error", // Disallows the use of var, enforcing let or const instead
+        "prefer-const": "error", // Prefers the use of const for variables that are never reassigned
+        "no-undef": "off", // Disables the rule that disallows the use of undeclared variables (TypeScript handles this)
+        "@typescript-eslint/no-unused-vars": [ "error", {
+          "args": "none", // Allows unused function parameters. Useful for functions with specific signatures where not all parameters are always used.
+          "ignoreRestSiblings": true // Allows unused variables that are part of a rest property in object destructuring. Useful for excluding certain properties from an object while using the rest.
+        }],
+        "eol-last": ["error", "always"], // Enforces at least one newline at the end of files
+        "@typescript-eslint/semi": ["error", "always"], // Requires semicolons for TypeScript-specific syntax
+        "semi": "off", // Disables the general semi rule for TypeScript files
+        "@typescript-eslint/no-extra-semi": ["error"], // Disallows unnecessary semicolons for TypeScript-specific syntax
+        "brace-style": "off", // Note: you must disable the base rule as it can report incorrect errors
+        "curly": ["error", "all"], // Enforces the use of curly braces for all control statements
+        "@typescript-eslint/brace-style": ["error", "1tbs"]
+      }
+    }
+  ]
 }

.github/workflows/eslint.yml

@@ -0,0 +1,31 @@
+name: ESLint
+
+on:
+  # Trigger the workflow on push or pull request,
+  # but only for the main branch
+  push:
+    branches:
+      - main  # Trigger on push events to the main branch
+  pull_request:
+    branches:
+      - main  # Trigger on pull request events targeting the main branch
+
+jobs:
+  run-linters:  # Define a job named "run-linters"
+    name: Run linters  # Human-readable name for the job
+    runs-on: ubuntu-latest  # Specify the latest Ubuntu runner for the job
+
+    steps:
+      - name: Check out Git repository  # Step to check out the repository
+        uses: actions/checkout@v2  # Use the checkout action version 2
+
+      - name: Set up Node.js  # Step to set up Node.js environment
+        uses: actions/setup-node@v1  # Use the setup-node action version 1
+        with:
+          node-version: 20  # Specify Node.js version 20
+
+      - name: Install Node.js dependencies  # Step to install Node.js dependencies
+        run: npm ci  # Use 'npm ci' to install dependencies
+
+      - name: eslint  # Step to run linters
+        uses: icrawl/action-eslint@v1

lefthook.yml

@@ -0,0 +1,7 @@
+pre-commit:
+  parallel: true
+  commands:
+    eslint:
+      glob: '*.{js,jsx,ts,tsx}'
+      run: npx eslint --fix {staged_files}
+      stage_fixed: true