New: html-self-closing rule (fixes #31)

docs/rules/html-self-closing-style.md

@@ -0,0 +1,67 @@
+# Enforce self-closing style (html-self-closing-style)
+
+In Vue.js template, we can use either two styles for elements which don't have their content.
+
+1. `<your-component></your-component>`
+2. `<your-component />` (self-closing)
+
+Self-closing is simple and shorter, but it's not supported in raw HTML.
+This rule helps you to unify the self-closing style.
+
+## Rule Details
+
+This rule has options which specify self-closing style for each context.
+
+```json
+{
+    "html-self-closing-style": ["error", {
+        "html": {
+            "normal": "never",
+            "void": "never",
+            "component": "always"
+        },
+        "svg": "always",
+        "math": "always"
+    }]
+}
+```
+
+- `html.normal` (`"never"` by default) ... The style of well-known HTML elements except void elements.
+- `html.void` (`"never"` by default) ... The style of well-known HTML void elements.
+- `html.component` (`"always"` by default) ... The style of Vue.js custom components.
+- `svg`(`"always"` by default) .... The style of well-known SVG elements.
+- `math`(`"always"` by default) .... The style of well-known MathML elements.
+
+Every option can be set to one of the following values:
+
+- `"always"` ... Require self-closing at elements which don't have their content.
+- `"never"` ... Disallow self-closing.
+- `"any"` ... Don't enforce self-closing style.
+
+----
+
+:-1: Examples of **incorrect** code for this rule:
+
+```html
+/*eslint html-self-closing-style: "error"*/
+
+<template>
+    <div />
+    <img />
+    <your-component></your-component>
+    <svg><path d=""></path></svg>
+</template>
+```
+
+:+1: Examples of **correct** code for this rule:
+
+```html
+/*eslint html-self-closing-style: "error"*/
+
+<template>
+    <div></div>
+    <img>
+    <your-component />
+    <svg><path d="" /></svg>
+</template>
+```

lib/rules/html-end-tags.js

@@ -25,7 +25,7 @@ function create (context) {
   utils.registerTemplateBodyVisitor(context, {
     VElement (node) {
       const name = node.name
-      const isVoid = utils.isVoidElementName(name)
+      const isVoid = utils.isHtmlVoidElementName(name)
       const hasEndTag = node.endTag != null
 
       if (isVoid && hasEndTag) {

lib/rules/html-no-self-closing.js

@@ -57,7 +57,7 @@ module.exports = {
       description: 'disallow self-closing elements.',
       category: 'Best Practices',
       recommended: false,
-      replacedBy: []
+      replacedBy: ['html-self-closing-style']
     },
     deprecated: true,
     fixable: 'code',

lib/rules/html-self-closing-style.js

@@ -0,0 +1,179 @@
+/**
+ * @author Toru Nagashima
+ * @copyright 2016 Toru Nagashima. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const utils = require('../utils')
+
+// ------------------------------------------------------------------------------
+// Helpers
+// ------------------------------------------------------------------------------
+
+/**
+ * Kind strings.
+ * This strings wil be displayed in error messages.
+ */
+const KIND = Object.freeze({
+  NORMAL: 'HTML elements',
+  VOID: 'HTML void elements',
+  COMPONENT: 'Vue.js custom components',
+  SVG: 'SVG elements',
+  MATH: 'MathML elements'
+})
+
+/**
+ * Normalize the given options.
+ * @param {Object|undefined} options The raw options object.
+ * @returns {Object} Normalized options.
+ */
+function parseOptions (options) {
+  return {
+    [KIND.NORMAL]: (options && options.html && options.html.normal) || 'never',
+    [KIND.VOID]: (options && options.html && options.html.void) || 'never',
+    [KIND.COMPONENT]: (options && options.html && options.html.component) || 'always',
+    [KIND.SVG]: (options && options.svg) || 'always',
+    [KIND.MATH]: (options && options.math) || 'always'
+  }
+}
+
+/**
+ * Get the kind of the given element.
+ * @param {VElement} node The element node to get.
+ * @returns {string} The kind of the element.
+ */
+function getKind (node) {
+  if (utils.isCustomComponent(node)) {
+    return KIND.COMPONENT
+  }
+  if (utils.isHtmlElementNode(node)) {
+    if (utils.isHtmlVoidElementName(node.name)) {
+      return KIND.VOID
+    }
+    return KIND.NORMAL
+  }
+  if (utils.isSvgElementNode(node)) {
+    return KIND.SVG
+  }
+  if (utils.isMathMLElementNode(node)) {
+    return KIND.MATH
+  }
+  return 'unknown elements'
+}
+
+/**
+ * Check whether the given element is empty or not.
+ * This ignores whitespaces, doesn't ignore comments.
+ * @param {VElement} node The element node to check.
+ * @returns {boolean} `true` if the element is empty.
+ */
+function isEmpty (node, sourceCode) {
+  const start = node.startTag.range[1]
+  const end = (node.endTag != null) ? node.endTag.range[0] : node.range[1]
+
+  return sourceCode.text.slice(start, end).trim() === ''
+}
+
+/**
+ * Creates AST event handlers for html-self-closing-style.
+ *
+ * @param {RuleContext} context - The rule context.
+ * @returns {object} AST event handlers.
+ */
+function create (context) {
+  const sourceCode = context.getSourceCode()
+  const options = parseOptions(context.options[0])
+
+  utils.registerTemplateBodyVisitor(context, {
+    'VElement' (node) {
+      const kind = getKind(node)
+      const mode = options[kind]
+
+      if (mode === 'always' && !node.startTag.selfClosing && isEmpty(node, sourceCode)) {
+        context.report({
+          node,
+          loc: node.loc,
+          message: 'Require self-closing on {{kind}}.',
+          data: { kind },
+          fix: (fixer) => {
+            const tokens = context.parserServices.getTemplateBodyTokenStore()
+            const close = tokens.getLastToken(node.startTag)
+            if (close.type !== 'HTMLTagClose') {
+              return null
+            }
+            return fixer.replaceTextRange([close.range[0], node.range[1]], '/>')
+          }
+        })
+      }
+
+      if (mode === 'never' && node.startTag.selfClosing) {
+        context.report({
+          node,
+          loc: node.loc,
+          message: 'Disallow self-closing on {{kind}}.',
+          data: { kind },
+          fix: (fixer) => {
+            const tokens = context.parserServices.getTemplateBodyTokenStore()
+            const close = tokens.getLastToken(node.startTag)
+            if (close.type !== 'HTMLSelfClosingTagClose') {
+              return null
+            }
+            if (kind === KIND.VOID) {
+              return fixer.replaceText(close, '>')
+            }
+            return fixer.replaceText(close, `></${node.rawName}>`)
+          }
+        })
+      }
+    }
+  })
+
+  return {}
+}
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+module.exports = {
+  create,
+  meta: {
+    docs: {
+      description: 'enforce self-closing style.',
+      category: 'Stylistic Issues',
+      recommended: false
+    },
+    fixable: 'code',
+    schema: {
+      definitions: {
+        optionValue: {
+          enum: ['always', 'never', 'any']
+        }
+      },
+      type: 'array',
+      items: [{
+        type: 'object',
+        properties: {
+          html: {
+            type: 'object',
+            properties: {
+              normal: { $ref: '#/definitions/optionValue' },
+              void: { $ref: '#/definitions/optionValue' },
+              component: { $ref: '#/definitions/optionValue' }
+            },
+            additionalProperties: false
+          },
+          svg: { $ref: '#/definitions/optionValue' },
+          math: { $ref: '#/definitions/optionValue' }
+        },
+        additionalProperties: false
+      }],
+      maxItems: 1
+    }
+  }
+}

lib/utils/index.js

@@ -183,7 +183,7 @@ module.exports = {
     assert(node && node.type === 'VElement')
 
     return (
-      !(this.isKnownHtmlElementNode(node) || this.isSvgElementNode(node) || this.isMathMLElementNode(node)) ||
+      (this.isHtmlElementNode(node) && !this.isHtmlWellKnownElementName(node.name)) ||
       this.hasAttribute(node, 'is') ||
       this.hasDirective(node, 'bind', 'is')
     )
@@ -194,10 +194,10 @@ module.exports = {
    * @param {ASTNode} node The node to check.
    * @returns {boolean} `true` if the node is a HTML element.
    */
-  isKnownHtmlElementNode (node) {
+  isHtmlElementNode (node) {
     assert(node && node.type === 'VElement')
 
-    return node.namespace === vueEslintParser.AST.NS.HTML && HTML_ELEMENT_NAMES.has(node.name.toLowerCase())
+    return node.namespace === vueEslintParser.AST.NS.HTML
   },
 
   /**
@@ -222,12 +222,23 @@ module.exports = {
     return node.namespace === vueEslintParser.AST.NS.MathML
   },
 
+  /**
+   * Check whether the given name is an well-known element or not.
+   * @param {string} name The name to check.
+   * @returns {boolean} `true` if the name is an well-known element name.
+   */
+  isHtmlWellKnownElementName (name) {
+    assert(typeof name === 'string')
+
+    return HTML_ELEMENT_NAMES.has(name.toLowerCase())
+  },
+
   /**
    * Check whether the given name is a void element name or not.
    * @param {string} name The name to check.
    * @returns {boolean} `true` if the name is a void element name.
    */
-  isVoidElementName (name) {
+  isHtmlVoidElementName (name) {
     assert(typeof name === 'string')
 
     return VOID_ELEMENT_NAMES.has(name.toLowerCase())