Meta: Install eslint-plugin-unicorn (#1857)

* Install `eslint-plugin-unicorn`

* Fix new lint issues

.eslintrc.js

@@ -14,9 +14,10 @@ module.exports = {
     'plugin:eslint-plugin/recommended',
     'prettier',
     'plugin:node-dependencies/recommended',
-    'plugin:jsonc/recommended-with-jsonc'
+    'plugin:jsonc/recommended-with-jsonc',
+    'plugin:unicorn/recommended'
   ],
-  plugins: ['eslint-plugin', 'prettier'],
+  plugins: ['eslint-plugin', 'prettier', 'unicorn'],
   rules: {
     'accessor-pairs': 2,
     camelcase: [2, { properties: 'never' }],
@@ -117,7 +118,19 @@ module.exports = {
     'prefer-arrow-callback': 'error',
     'prefer-spread': 'error',
 
-    'dot-notation': 'error'
+    'dot-notation': 'error',
+
+    'unicorn/consistent-function-scoping': [
+      'error',
+      { checkArrowFunctions: false }
+    ],
+    'unicorn/filename-case': 'off',
+    'unicorn/no-null': 'off',
+    'unicorn/no-array-callback-reference': 'off', // doesn't work well with TypeScript's custom type guards
+    'unicorn/no-useless-undefined': 'off',
+    'unicorn/prefer-optional-catch-binding': 'off', // not supported by current ESLint parser version
+    'unicorn/prefer-module': 'off',
+    'unicorn/prevent-abbreviations': 'off'
   },
   overrides: [
     {

docs/.vuepress/enhanceApp.js

@@ -8,21 +8,19 @@ export default (
     //     siteData, // site metadata
   }
 ) => {
-  if (typeof window !== 'undefined') {
-    if (typeof window.process === 'undefined') {
-      window.process = new Proxy(
-        {
-          env: {},
-          cwd: () => undefined
-        },
-        {
-          get(target, name) {
-            // For debug
-            // console.log(name)
-            return target[name]
-          }
+  if (typeof window !== 'undefined' && typeof window.process === 'undefined') {
+    window.process = new Proxy(
+      {
+        env: {},
+        cwd: () => undefined
+      },
+      {
+        get(target, name) {
+          // For debug
+          // console.log(name)
+          return target[name]
         }
-      )
-    }
+      }
+    )
   }
 }

eslint-internal-rules/no-invalid-meta-docs-categories.js

@@ -12,17 +12,17 @@
 /**
  * Gets the property of the Object node passed in that has the name specified.
  *
- * @param {string} property Name of the property to return.
+ * @param {string} propertyName Name of the property to return.
  * @param {ASTNode} node The ObjectExpression node.
  * @returns {ASTNode} The Property node or null if not found.
  */
-function getPropertyFromObject(property, node) {
+function getPropertyFromObject(propertyName, node) {
   if (node && node.type === 'ObjectExpression') {
     const properties = node.properties
 
-    for (let i = 0; i < properties.length; i++) {
-      if (properties[i].key.name === property) {
-        return properties[i]
+    for (const property of properties) {
+      if (property.key.name === propertyName) {
+        return property
       }
     }
   }

eslint-internal-rules/no-invalid-meta.js

@@ -12,17 +12,17 @@
 /**
  * Gets the property of the Object node passed in that has the name specified.
  *
- * @param {string} property Name of the property to return.
+ * @param {string} propertyName Name of the property to return.
  * @param {ASTNode} node The ObjectExpression node.
  * @returns {ASTNode} The Property node or null if not found.
  */
-function getPropertyFromObject(property, node) {
+function getPropertyFromObject(propertyName, node) {
   if (node && node.type === 'ObjectExpression') {
     const properties = node.properties
 
-    for (let i = 0; i < properties.length; i++) {
-      if (properties[i].key.name === property) {
-        return properties[i]
+    for (const property of properties) {
+      if (property.key.name === propertyName) {
+        return property
       }
     }
   }

lib/processor.js

@@ -84,10 +84,10 @@ module.exports = {
         return false
       } else {
         const disableDirectiveKeys = []
-        if (state.block.disableAllKeys.size) {
+        if (state.block.disableAllKeys.size > 0) {
           disableDirectiveKeys.push(...state.block.disableAllKeys)
         }
-        if (state.line.disableAllKeys.size) {
+        if (state.line.disableAllKeys.size > 0) {
           disableDirectiveKeys.push(...state.line.disableAllKeys)
         }
         if (message.ruleId) {
@@ -101,7 +101,7 @@ module.exports = {
           }
         }
 
-        if (disableDirectiveKeys.length) {
+        if (disableDirectiveKeys.length > 0) {
           // Store used eslint-disable comment key
           usedDisableDirectiveKeys.push(...disableDirectiveKeys)
           return false
@@ -111,7 +111,7 @@ module.exports = {
       }
     })
 
-    if (unusedDisableDirectiveReports.size) {
+    if (unusedDisableDirectiveReports.size > 0) {
       for (const key of usedDisableDirectiveKeys) {
         // Remove used eslint-disable comments
         unusedDisableDirectiveReports.delete(key)

lib/rules/attribute-hyphenation.js

@@ -12,6 +12,26 @@ const svgAttributes = require('../utils/svg-attributes-weird-case.json')
 // Rule Definition
 // ------------------------------------------------------------------------------
 
+/**
+ * @param {VDirective | VAttribute} node
+ * @returns {string | null}
+ */
+function getAttributeName(node) {
+  if (!node.directive) {
+    return node.key.rawName
+  }
+
+  if (
+    node.key.name.name === 'bind' &&
+    node.key.argument &&
+    node.key.argument.type === 'VIdentifier'
+  ) {
+    return node.key.argument.rawName
+  }
+
+  return null
+}
+
 module.exports = {
   meta: {
     type: 'suggestion',
@@ -52,12 +72,10 @@ module.exports = {
     const option = context.options[0]
     const optionsPayload = context.options[1]
     const useHyphenated = option !== 'never'
-    let ignoredAttributes = ['data-', 'aria-', 'slot-scope'].concat(
-      svgAttributes
-    )
+    const ignoredAttributes = ['data-', 'aria-', 'slot-scope', ...svgAttributes]
 
     if (optionsPayload && optionsPayload.ignore) {
-      ignoredAttributes = ignoredAttributes.concat(optionsPayload.ignore)
+      ignoredAttributes.push(...optionsPayload.ignore)
     }
 
     const caseConverter = casing.getExactConverter(
@@ -112,14 +130,8 @@ module.exports = {
         )
           return
 
-        const name = !node.directive
-          ? node.key.rawName
-          : node.key.name.name === 'bind'
-          ? node.key.argument &&
-            node.key.argument.type === 'VIdentifier' &&
-            node.key.argument.rawName
-          : /* otherwise */ false
-        if (!name || isIgnoredAttribute(name)) return
+        const name = getAttributeName(node)
+        if (name === null || isIgnoredAttribute(name)) return
 
         reportIssue(node, name)
       }

lib/rules/attributes-order.js

@@ -111,30 +111,31 @@ function getAttributeType(attribute) {
   if (attribute.directive) {
     if (!isVBind(attribute)) {
       const name = attribute.key.name.name
-      if (name === 'for') {
-        return ATTRS.LIST_RENDERING
-      } else if (
-        name === 'if' ||
-        name === 'else-if' ||
-        name === 'else' ||
-        name === 'show' ||
-        name === 'cloak'
-      ) {
-        return ATTRS.CONDITIONALS
-      } else if (name === 'pre' || name === 'once') {
-        return ATTRS.RENDER_MODIFIERS
-      } else if (name === 'model') {
-        return ATTRS.TWO_WAY_BINDING
-      } else if (name === 'on') {
-        return ATTRS.EVENTS
-      } else if (name === 'html' || name === 'text') {
-        return ATTRS.CONTENT
-      } else if (name === 'slot') {
-        return ATTRS.SLOT
-      } else if (name === 'is') {
-        return ATTRS.DEFINITION
-      } else {
-        return ATTRS.OTHER_DIRECTIVES
+      switch (name) {
+        case 'for':
+          return ATTRS.LIST_RENDERING
+        case 'if':
+        case 'else-if':
+        case 'else':
+        case 'show':
+        case 'cloak':
+          return ATTRS.CONDITIONALS
+        case 'pre':
+        case 'once':
+          return ATTRS.RENDER_MODIFIERS
+        case 'model':
+          return ATTRS.TWO_WAY_BINDING
+        case 'on':
+          return ATTRS.EVENTS
+        case 'html':
+        case 'text':
+          return ATTRS.CONTENT
+        case 'slot':
+          return ATTRS.SLOT
+        case 'is':
+          return ATTRS.DEFINITION
+        default:
+          return ATTRS.OTHER_DIRECTIVES
       }
     }
     propName =
@@ -144,16 +145,19 @@ function getAttributeType(attribute) {
   } else {
     propName = attribute.key.name
   }
-  if (propName === 'is') {
-    return ATTRS.DEFINITION
-  } else if (propName === 'id') {
-    return ATTRS.GLOBAL
-  } else if (propName === 'ref' || propName === 'key') {
-    return ATTRS.UNIQUE
-  } else if (propName === 'slot' || propName === 'slot-scope') {
-    return ATTRS.SLOT
-  } else {
-    return ATTRS.OTHER_ATTR
+  switch (propName) {
+    case 'is':
+      return ATTRS.DEFINITION
+    case 'id':
+      return ATTRS.GLOBAL
+    case 'ref':
+    case 'key':
+      return ATTRS.UNIQUE
+    case 'slot':
+    case 'slot-scope':
+      return ATTRS.SLOT
+    default:
+      return ATTRS.OTHER_ATTR
   }
 }
 
@@ -213,13 +217,13 @@ function create(context) {
 
   /** @type { { [key: string]: number } } */
   const attributePosition = {}
-  attributeOrder.forEach((item, i) => {
+  for (const [i, item] of attributeOrder.entries()) {
     if (Array.isArray(item)) {
       for (const attr of item) {
         attributePosition[attr] = i
       }
     } else attributePosition[item] = i
-  })
+  }
 
   /**
    * @param {VAttribute | VDirective} node
@@ -319,8 +323,7 @@ function create(context) {
     })
 
     const results = []
-    for (let index = 0; index < attributes.length; index++) {
-      const attr = attributes[index]
+    for (const [index, attr] of attributes.entries()) {
       const position = getPositionFromAttrIndex(index)
       if (position == null) {
         // The omitted order is skipped.

lib/rules/block-lang.js

@@ -52,13 +52,21 @@ function getAllowsLangPhrase(lang) {
 /**
  * Normalizes a given option.
  * @param {string} blockName The block name.
- * @param { UserBlockOptions } option An option to parse.
+ * @param {UserBlockOptions} option An option to parse.
  * @returns {BlockOptions} Normalized option.
  */
 function normalizeOption(blockName, option) {
-  const lang = new Set(
-    Array.isArray(option.lang) ? option.lang : option.lang ? [option.lang] : []
-  )
+  /** @type {Set<string>} */
+  let lang
+
+  if (Array.isArray(option.lang)) {
+    lang = new Set(option.lang)
+  } else if (typeof option.lang === 'string') {
+    lang = new Set([option.lang])
+  } else {
+    lang = new Set()
+  }
+
   let hasDefault = false
   for (const def of DEFAULT_LANGUAGES[blockName] || []) {
     if (lang.has(def)) {
@@ -165,8 +173,7 @@ module.exports = {
         style: { allowNoLang: true }
       }
     )
-    if (!Object.keys(options).length) {
-      // empty
+    if (Object.keys(options).length === 0) {
       return {}
     }
 
@@ -198,11 +205,9 @@ module.exports = {
         if (!option.allowNoLang) {
           messageId = 'expected'
         } else if (option.lang.size === 0) {
-          if ((DEFAULT_LANGUAGES[tag] || []).includes(lang.value.value)) {
-            messageId = 'unexpectedDefault'
-          } else {
-            messageId = 'unexpected'
-          }
+          messageId = (DEFAULT_LANGUAGES[tag] || []).includes(lang.value.value)
+            ? 'unexpectedDefault'
+            : 'unexpected'
         } else {
           messageId = 'useOrNot'
         }

lib/rules/block-tag-newline.js

@@ -257,9 +257,8 @@ module.exports = {
       }
 
       const option =
-        options.multiline === options.singleline
-          ? options.singleline
-          : /[\n\r\u2028\u2029]/u.test(text.trim())
+        options.multiline !== options.singleline &&
+        /[\n\r\u2028\u2029]/u.test(text.trim())
           ? options.multiline
           : options.singleline
       if (option === 'ignore') {