feat: support writing HTML(Vue) anywhere in the header.

lib/util/parseHeaders.js

@@ -1,3 +1,15 @@
+// Since VuePress needs to extract the header from the markdown source
+// file and display it in the sidebar or title (#238), this file simply
+// removes some unnecessary elements to make header displays well at
+// sidebar or title.
+//
+// But header's parsing in the markdown content is done by the markdown
+// loader based on markdown-it. markdown-it parser will will always keep
+// HTML in headers, so in VuePress, after being parsed by the markdiwn
+// loader, the raw HTML in headers will finally be parsed by Vue-loader.
+// so that we can write HTML/Vue in the header. One exception is the HTML
+// wrapped by <code>(markdown token: '`') tag.
+
 const { compose } = require('./shared')
 
 const parseEmojis = str => {
@@ -12,26 +24,33 @@ const unescapeHtml = html => String(html)
   .replace(/&lt;/g, '<')
   .replace(/&gt;/g, '>')
 
-const removeMarkdownToken = str => String(str)
+const removeMarkdownTokens = str => String(str)
   .replace(/\[(.*)\]\(.*\)/, '$1')              // []()
   .replace(/(`|\*{1,3}|_)(.*?[^\\])\1/g, '$2')  // `{t}` | *{t}* | **{t}** | ***{t}*** | _{t}_
   .replace(/(\\)(\*|_|`)/g, '$2')               // remove escape char '\'
 
-exports.removeTailHtml = (str) => {
-  return String(str).replace(/\s*?<.*>\s*$/g, '')
+const trim = str => str.trim()
+
+// This method remove the raw HTML but reserve the HTML wrapped by `<code>`.
+// e.g.
+// Input: "<a> b",   Output: "b"
+// Input: "`<a>` b", Output: "`<a>` b"
+exports.removeNonCodeWrappedHTML = (str) => {
+  return String(str).replace(/(^|[^><`])<.*>([^><`]|$)/g, '$1$2')
 }
 
-// Only remove some md tokens.
+// Unescape html, parse emojis and remove some md tokens.
 exports.parseHeaders = compose(
   unescapeHtml,
   parseEmojis,
-  removeMarkdownToken
+  removeMarkdownTokens,
+  trim
 )
 
-// Also clean the tail html in headers.
-// Since we want to support tailed badge in headers.
-// See: https://vuepress.vuejs.org/guide/using-vue.html#badge
+// Also clean the html that isn't wrapped by code.
+// Because we want to support using VUE components in headers.
+// e.g. https://vuepress.vuejs.org/guide/using-vue.html#badge
 exports.deeplyParseHeaders = compose(
-  exports.removeTailHtml,
+  exports.removeNonCodeWrappedHTML,
   exports.parseHeaders,
 )

test/util/parseHeaders.spec.js

@@ -1,6 +1,6 @@
 import {
   parseHeaders,
-  removeTailHtml,
+  removeNonCodeWrappedHTML,
   deeplyParseHeaders
 } from '@/util/parseHeaders'
 
@@ -32,15 +32,87 @@ describe('parseHeaders', () => {
     })
   })
 
-  test('should remove tail html correctly', () => {
-    expect(removeTailHtml('# H1 <Comp></Comp>')).toBe('# H1')
-    expect(removeTailHtml('# H1 <Comp a="b"></Comp>')).toBe('# H1')
-    expect(removeTailHtml('# H1 <Comp/>')).toBe('# H1')
-    expect(removeTailHtml('# H1 <Comp a="b"/>')).toBe('# H1')
+  test('should remove non-code-wrapped html correctly', () => {
+    const asserts = {
+      // Remove tail html
+      '# H1 <Comp></Comp>': '# H1 ',
+      '# H1<Comp></Comp>': '# H1',
+      '# H1 <Comp a="b"></Comp>': '# H1 ',
+      '# H1<Comp a="b"></Comp>': '# H1',
+      '# H1 <Comp/>': '# H1 ',
+      '# H1<Comp/>': '# H1',
+      '# H1 <Comp a="b"/>': '# H1 ',
+      '# H1<Comp a="b"/>': '# H1',
+
+      // Reserve code-wrapped tail html
+      '# H1 `<Comp></Comp>`': '# H1 `<Comp></Comp>`',
+      '# H1 `<Comp a="b"></Comp>`': '# H1 `<Comp a="b"></Comp>`',
+      '# H1 `<Comp/>`': '# H1 `<Comp/>`',
+      '# H1 `<Comp a="b"/>`': '# H1 `<Comp a="b"/>`',
+
+      // Remove leading html
+      '# <Comp></Comp> H1': '#  H1',
+      '# <Comp></Comp>H1': '# H1',
+      '# <Comp a="b"></Comp> H1': '#  H1',
+      '# <Comp a="b"></Comp>H1': '# H1',
+      '# <Comp/> H1': '#  H1',
+      '# <Comp/>H1': '# H1',
+      '# <Comp a="b"/> H1': '#  H1',
+      '# <Comp a="b"/>H1': '# H1',
+
+      // Reserve code-wrapped leading html
+      '# `<Comp></Comp>` H1': '# `<Comp></Comp>` H1',
+      '# `<Comp a="b"></Comp>` H1': '# `<Comp a="b"></Comp>` H1',
+      '# `<Comp/>` H1': '# `<Comp/>` H1',
+      '# `<Comp a="b"/>` H1': '# `<Comp a="b"/>` H1',
+
+      // Remove middle html
+      '# H1 <Comp></Comp> H2': '# H1  H2',
+      '# H1 <Comp a="b"></Comp> H2': '# H1  H2',
+      '# H1 <Comp/> H2': '# H1  H2',
+      '# H1 <Comp a="b"/> H2': '# H1  H2',
+
+      // Reserve code-wrapped middle html
+      '# H1 `<Comp></Comp>` H2': '# H1 `<Comp></Comp>` H2',
+      '# H1 `<Comp a="b"></Comp>` H2': '# H1 `<Comp a="b"></Comp>` H2',
+      '# H1 `<Comp/>` H2': '# H1 `<Comp/>` H2',
+      '# H1 `<Comp a="b"/>` H2': '# H1 `<Comp a="b"/>` H2'
+    }
+
+    Object.keys(asserts).forEach(input => {
+      expect(removeNonCodeWrappedHTML(input)).toBe(asserts[input])
+    })
   })
 
   test('should deeplyParseHeaders transformed as expected', () => {
-    expect(deeplyParseHeaders('# `H1` <Comp></Comp>')).toBe('# H1')
-    expect(deeplyParseHeaders('# *H1* <Comp/>')).toBe('# H1')
+    const asserts = {
+      // Remove tail html
+      '# `H1` <Comp></Comp>': '# H1',
+      '# *H1* <Comp/>': '# H1',
+
+      // Reserve code-wrapped tail html
+      '# `H1` `<Comp></Comp>`': '# H1 <Comp></Comp>',
+      '# *H1* `<Comp/>`': '# H1 <Comp/>',
+
+      // Remove leading html
+      '# <Comp></Comp> `H1`': '#  H1',
+      '# <Comp/> *H1*': '#  H1',
+
+      // Reserve code-wrapped leading html
+      '# `<Comp></Comp>` `H1`': '# <Comp></Comp> H1',
+      '# `<Comp/>` *H1*': '# <Comp/> H1',
+
+      // Remove middle html
+      '# `H1` <Comp></Comp> `H2`': '# H1  H2',
+      '# `H1` <Comp/> `H2`': '# H1  H2',
+
+      // Reserve middle html
+      '# `H1` `<Comp></Comp>` `H2`': '# H1 <Comp></Comp> H2',
+      '# `H1` `<Comp/>` `H2`': '# H1 <Comp/> H2'
+    }
+
+    Object.keys(asserts).forEach(input => {
+      expect(deeplyParseHeaders(input)).toBe(asserts[input])
+    })
   })
 })