.eslintrc

{
  root: true,

  parserOptions: {
    // use babel-eslint for ES6
    parser: "babel-eslint",
    ecmaVersion: 6,
    sourceType: "module",
    ecmaFeatures: {
      jsx: false,
      modules: true
    }
  },

  env: {
    es6: true,
    node: true,
    browser: true
  },

  // global variables that should bypass checking, share the same value as
  // the `externals` field of webpack config
  // p.s. different app uses different globals
  globals: {
    PAGE_PAYLOAD: true,
    CONFIG: true
  },

  extends: [
    "eslint:recommended",
    "plugin:prettier/recommended",
    "plugin:vue/recommended"
  ],

  rules: {
    // us strictly equal operator
    eqeqeq: "error",

    // line breaks should follow the operators, e.g. the && operator used
    // inside multiple conditions should be put at the end of the previous line
    "operator-linebreak": [
      "error",
      "after",
      {
        // ternary operators should be placed at the beginning of the line
        overrides: {
          "?": "ignore",
          ":": "ignore"
        }
      }
    ],

    // code blocks must be enclosed by curly brackets
    curly: "error",

    // indent chained operations
    "newline-per-chained-call": "error",

    // key-value pairs inside an object should be put into separated lines
    "object-property-newline": [
      "error",
      {
        // all properties in the same line is not allowed
        allowAllPropertiesOnSameLine: false
      }
    ],

    // add line breaks for all properties if there is a property has line
    // break, otherwise keep all of them in the same line
    "object-curly-newline": [
      "error",
      {
        // 对象申明的花括号，如果不换就都不换，如果换都换，只有一个键值对就不换，为空不换
        // 只有一个键值对，但是导致本行超长，就要换（比如函数最后一个对象参数里面的键
        // 是一个超长字符串）
        ObjectExpression: { consistent: true },
        // 赋值解构，要换都换，否则不换
        ObjectPattern: { multiline: true },
        // import 语句，两个及以上就要换
        ImportDeclaration: { consistent: true },
        // export 语句，要换都换，要不换都不换，如果不换导致本行超长，则全部换
        ExportDeclaration: { consistent: true }
      }
    ],

    // always use double quotes
    quotes: [
      "error",
      "double",
      {
        // do not escape double quotes which are inside single quote pairs,
        // the same rule applys to single quotes
        avoidEscape: true,
        // allow template literals
        allowTemplateLiterals: true
      }
    ],

    // only wrap up object keys inside quotes when it's necessary
    // note that if we don't explicitly config this rule the vue eslint plugin
    // will simply ignore it.
    "quote-props": ["error", "as-needed"],

    // disable inline comments
    "no-inline-comments": ["error"],

    // the opening curly bracket of a code block should stay in the end of the
    // first line
    "brace-style": [2, "1tbs"],

    // remove blank lines at the beginning and the end of a block
    "padded-blocks": ["error", "never"],

    // line breaks inside code blocks
    "padding-line-between-statements": [
      "error",

      // break line before `if`
      {
        blankLine: "always",
        prev: "*",
        next: "if"
      },
      // break line before `for`
      {
        blankLine: "always",
        prev: "*",
        next: "for"
      },
      // break line before `return`
      {
        blankLine: "always",
        prev: "*",
        next: "return"
      },
      // break line before `function`
      {
        blankLine: "always",
        prev: "*",
        next: "function"
      }
    ],

    // no space before function opening parenthesis
    "space-before-function-paren": ["error", "never"],

    // no space between it's name and the parenthesis pairs while calling
    // a function
    "func-call-spacing": ["error", "never"],

    // start comments with white spaces, either single line or multi-line
    // comments
    "spaced-comment": ["error", "always"],

    "arrow-spacing": ["error"],

    // force using semicolons to end a line
    semi: ["error", "always"],

    // do not put white spaces before a semicolon, but there must be white
    // spaces after it.
    "semi-spacing": [
      "error",
      {
        before: false,
        after: true
      }
    ],

    // put white spaces before a code block
    "space-before-blocks": ["error"],

    // there must be white spaces around an operator like `+`
    "space-infix-ops": ["error"],

    // disallow white spaces before colons, but there must be white spaces
    // after it. e.g. var a = 3, b = 4;
    "comma-spacing": [
      "error",
      {
        before: false,
        after: true
      }
    ],

    // disallow multiple white spaces. e.g. let    a =  33;
    "no-multi-spaces": ["error"],

    // put white spaces around keywords. e.g. if (xxx)
    "keyword-spacing": [
      "error",
      {
        before: true,
        after: true
      }
    ],

    // disallow trailing commas, including: array/object/export/import/function
    "comma-dangle": [
      "error",
      {
        // after the last argument of a function there shouldn't be commas
        functions: "never"
      }
    ],

    // put white spaces after object keys
    "key-spacing": ["error", { afterColon: true }],

    // maximum line length up to 80 characters
    "max-len": [
      "error",
      {
        code: 80,
        // ignore tempelate literals that exceeds the limit
        ignoreTemplateLiterals: true,
        // ignore regexp literals
        ignoreRegExpLiterals: true,
        // ignore urls
        ignoreUrls: true,
        // ignore import states
        ignorePattern: "^\\s*import\\s+.+\\s+from\\s+.+;$"
      }
    ],

    // break lines for every argument of a function simultaneously if one
    // of them has line break.
    "function-paren-newline": ["error", "consistent"],

    // line breaks inside templates
    // this conflicts with prettier!
    "vue/max-attributes-per-line": [
      2,
      {
        singleline: 1,
        multiline: {
          max: 1,
          // 第一个属性不用换行：必须换行（目前和 prettier 冲突，prettier 会强制
          // 换行）
          allowFirstLine: false
        }
      }
    ],

    // enforce self closing on tags
    "vue/html-self-closing": [
      "error",
      {
        html: {
          // `img` and the like should close in `/>`
          void: "always",
          // never self-close a non-self-closing element like `<p>`
          normal: "never",
          component: "never"
        },
        svg: "never",
        math: "never"
      }
    ],

    // use `camalCase` for props inside templates
    "vue/attribute-hyphenation": [
      2,
      "never",
      {
        // exception： custom-prop: customized non-props properties
        // e.g. abc-def="777"
        ignore: ["data-", "aria-", "custom-prop"]
      }
    ],

    // component name should use lower case and `kebab-case`
    "vue/name-property-casing": ["error", "kebab-case"]
  },

  // add exception rules
  overrides: [
    {
      files: ["*.vue"],
      rules: {
        // let prettier handle the "formatting" related tasks, while
        // eslint should be limited to do only static analysis related tasks
        // like syntax checking and fixing
        indent: "off",
        "vue/script-indent": "off",
        "vue/html-indent": "off",
        "vue/singleline-html-element-content-newline": "off"
      }
    },

    // `console` can be used inside NodeJS scripts
    {
      files: ["arch/**/*.js", "apps/*/utils/**/*.js"],
      rules: {
        "no-console": 0
      }
    },

    // mocha unit tests and global variables
    {
      files: ["apps/*/test/**/*.spec.js"],
      globals: {
        // ignore the global functions used by mocha
        describe: true,
        before: true,
        after: true,
        beforeEach: true,
        afterEach: true,
        it: true
      }
    }
  ]
}