switch to eslint (cocos#7727)

* switch to eslint

* eslint: extends airbnb

.editorconfig

@@ -9,4 +9,4 @@ end_of_line = lf
 indent_size = 4
 indent_style = space
 insert_final_newline = true
-trim_trailing_whitespace = true
+trim_trailing_whitespace = true

.eslintrc.yaml

@@ -0,0 +1,104 @@
+root: true
+
+parser: '@typescript-eslint/parser'
+
+parserOptions: 
+    project: ./tsconfig.json
+
+extends: 
+    - eslint:recommended
+    - airbnb-base
+    - plugin:@typescript-eslint/recommended
+    - plugin:@typescript-eslint/recommended-requiring-type-checking
+
+plugins:
+    - '@typescript-eslint'
+
+settings: 
+    import/resolver:
+        node: 
+            extensions: 
+                - .js
+                - .jsx
+                - .ts
+                - .tsx
+                - .d.ts
+
+env: 
+    browser: true
+    node: true
+    es6: true
+    jest: true
+
+globals: 
+    cc: false
+    wx: false
+    Editor: false
+    _Scene: false
+    _ccsg: false
+
+rules:
+
+    # https://eslint.org/docs/rules/
+    # https://github.com/typescript-eslint/typescript-eslint/tree/master/packages/eslint-plugin
+
+    ##### RECOMMENDED RULE OVERRIDES #####
+
+    camelcase: off # underscores may come in handy in some cases
+    eqeqeq: warn # important check missing from recommended
+    keyword-spacing: warn # we require this explicitly
+    no-multi-spaces: off # useful for manually align some expression across lines
+    prefer-rest-params: off # we need ES5 to be fast too
+    prefer-spread: off # we need ES5 to be fast too
+    space-before-function-paren: [warn, always] # we require this explicitly
+
+    ##### AIRBNB-SPECIFIC RULE OVERRIDES #####
+
+    class-methods-use-this: off # so empty functions could work
+    guard-for-in: off # for-in is a efficient choice for plain objects 
+    import/export: off # so export declare namespace could work
+    import/extensions: off # typescriptor doesn't support this
+    import/no-unresolved: off # TODO: fix internal modules
+    import/prefer-default-export: off # prefer seperate exports
+    indent: [warn, 4] # we use 4-space convention
+    lines-between-class-members: off # be more lenient on member declarations
+    max-classes-per-file: off # helper classes are common
+    max-len: [warn, 150] # more lenient on max length per line
+    new-cap: off # some class still doesn't follow this yet
+    no-underscore-dangle: off # allow underscores
+    no-plusplus: off # allow increment/decrement operators
+    no-console: off # allow console statements
+    no-continue: off # allow unlabeled continues
+    no-multi-assign: off # it is handy sometimes
+    no-param-reassign: off # the output object is passed as parameters all the time
+    no-restricted-syntax: off # for-in is a efficient choice for plain objects
+    no-return-assign: off # it is handy sometimes
+    no-shadow: off # TODO: this throws false-positives?
+    no-sequences: off # it is handy sometimes
+    no-bitwise: off # we use this extensively
+    no-use-before-define: off # just too much work
+    no-useless-constructor: off # gives false-positives for empty constructor with parameter properties
+
+    ##### TYPESCRIPT-SPECIFIC RULE OVERRIDES #####
+
+    # TODO: this is just too much work
+    '@typescript-eslint/explicit-module-boundary-types': off
+
+    # TODO: sadly we still rely heavily on legacyCC
+    '@typescript-eslint/no-unsafe-assignment': off
+    '@typescript-eslint/no-unsafe-call': off
+    '@typescript-eslint/no-unsafe-member-access': off
+
+    '@typescript-eslint/unbound-method': off # we exploit prototype methods sometimes to acheive better performace
+    '@typescript-eslint/no-explicit-any': off # still relevant for some heavily templated usages
+    '@typescript-eslint/no-empty-function': off # may become useful in some parent classes
+    '@typescript-eslint/no-unused-vars': off # may become useful in some parent classes
+    '@typescript-eslint/no-non-null-assertion': off # sometimes we just know better than the compiler
+    '@typescript-eslint/no-namespace': [warn, { # we need to declare static properties
+        allowDeclarations: true,
+        allowDefinitionFiles: true
+    }]
+    '@typescript-eslint/restrict-template-expressions': [warn, { # concatenations of different types are common, e.g. hash calculations
+        allowNumber: true,
+        allowBoolean: true
+    }]

.vscode/settings.json

@@ -15,5 +15,8 @@
     "eslint.validate": [
         "javascript",
         "typescript"
-    ]
+    ],
+    "editor.codeActionsOnSave": {
+        "source.fixAll": true,
+    },
 }

@types/globals.d.ts

@@ -25,6 +25,7 @@
 */
 
 declare const gfx: any;
+declare const global: any;
 
 interface Window {
 
@@ -62,7 +63,7 @@ interface HTMLElement{
 }
 
 type ActiveXObject = new (s: string) => any;
-declare var ActiveXObject: ActiveXObject;
+declare const ActiveXObject: ActiveXObject;
 
 declare type CompareFunction<T> = (a: T, b: T) => number;
 
@@ -81,7 +82,7 @@ declare interface IWritableArrayLike<T> {
     [index: number]: T;
 }
 
-declare type Constructor<T = {}> = new(...args: any[]) => T;
+declare type Constructor<T = unknown> = new(...args: any[]) => T;
 
 declare type Mutable<T> = { -readonly [P in keyof T]: T[P] };