feat: add GFM alerts support in markdown preview

README.md

@@ -21,6 +21,7 @@ Main features:
 - [Flowchart](https://github.com/adrai/flowchart.js)
 - [dot](https://github.com/mdaines/viz.js)
 - [Table of contents](https://github.com/nagaozen/markdown-it-toc-done-right)
+- [GitHub Flavored Markdown Alerts](https://github.com/antfu/markdown-it-github-alerts)
 - Emojis
 - Task lists
 - Local images
@@ -474,6 +475,7 @@ Vim support is powered by [@chemzqm/neovim](https://github.com/neoclide/neovim)
 - [markdown-it-katex](https://github.com/waylonflinn/markdown-it-katex)
 - [markdown-it-plantuml](https://github.com/gmunguia/markdown-it-plantuml)
 - [markdown-it-chart](https://github.com/tylingsoft/markdown-it-chart)
+- [markdown-it-github-alerts](https://github.com/antfu/markdown-it-github-alerts)
 - [mermaid](https://github.com/knsv/mermaid)
 - [opener](https://github.com/domenic/opener)
 - [sequence-diagrams](https://github.com/bramp/js-sequence-diagrams)

app/_static/markdown.css

@@ -18,6 +18,11 @@
     --color-markdown-table-border: #dfe2e5;
     --color-markdown-table-tr-border: #c6cbd1;
     --color-markdown-code-bg: #1b1f230d;
+    --color-note: #0969da;
+    --color-tip: #1a7f37;
+    --color-warning: #9a6700;
+    --color-caution: #d1242f;
+    --color-important: #8250df;
 }
 [data-theme="dark"] {
     --color-text-primary: #c9d1d9;
@@ -34,6 +39,11 @@
     --color-markdown-table-border: #3b434b;
     --color-markdown-table-tr-border: #272c32;
     --color-markdown-code-bg: #f0f6fc26;
+    --color-note: #2f81f7;
+    --color-tip: #3fb950;
+    --color-warning: #d29922;
+    --color-caution: #f85149;
+    --color-important: #a371f7;
 }
 
 .markdown-body ol ol,
@@ -189,6 +199,61 @@
   color: var(--color-text-tertiary);
   border-left: 4px solid var(--color-markdown-blockquote-border);
 }
+.markdown-body .markdown-alert {
+  padding: 0.5rem 1rem;
+  margin-bottom: 16px;
+  color: inherit;
+  border-left: 0.25em solid #888;
+}
+.markdown-body .markdown-alert > :first-child {
+  margin-top: 0;
+}
+.markdown-body .markdown-alert > :last-child {
+  margin-bottom: 0;
+}
+.markdown-body .markdown-alert .markdown-alert-title {
+  display: flex;
+  font-weight: 500;
+  align-items: center;
+  line-height: 1;
+}
+.markdown-body .markdown-alert .markdown-alert-title .octicon {
+  margin-right: 0.5rem;
+  display: inline-block;
+  overflow: visible !important;
+  vertical-align: text-bottom;
+  fill: currentColor;
+}
+.markdown-body .markdown-alert.markdown-alert-note {
+  border-left-color: var(--color-note);
+}
+.markdown-body .markdown-alert.markdown-alert-note .markdown-alert-title {
+  color: var(--color-note);
+}
+.markdown-body .markdown-alert.markdown-alert-important {
+  border-left-color: var(--color-important);
+}
+.markdown-body .markdown-alert.markdown-alert-important .markdown-alert-title {
+  color: var(--color-important);
+}
+.markdown-body .markdown-alert.markdown-alert-warning {
+  border-left-color: var(--color-warning);
+}
+.markdown-body .markdown-alert.markdown-alert-warning .markdown-alert-title {
+  color: var(--color-warning);
+}
+.markdown-body .markdown-alert.markdown-alert-tip {
+  border-left-color: var(--color-tip);
+}
+.markdown-body .markdown-alert.markdown-alert-tip .markdown-alert-title {
+  color: var(--color-tip);
+}
+.markdown-body .markdown-alert.markdown-alert-caution {
+  border-left-color: var(--color-caution);
+}
+.markdown-body .markdown-alert.markdown-alert-caution .markdown-alert-title {
+  color: var(--color-caution);
+}
 .markdown-body table {
   display: block;
   width: 100%;

app/pages/index.jsx

@@ -9,6 +9,7 @@ import footnote from 'markdown-it-footnote'
 import markdownItAnchor from 'markdown-it-anchor'
 import markdownItToc from 'markdown-it-toc-done-right'
 import markdownDeflist from 'markdown-it-deflist'
+import markdownItGitHubAlerts from './markdown-it-github-alerts-compat'
 
 import mk from './katex'
 import chart from './chart'
@@ -215,6 +216,7 @@ export default class PreviewPage extends React.Component {
         .use(taskLists)
         .use(markdownDeflist)
         .use(footnote)
+        .use(markdownItGitHubAlerts)
         .use(image)
         .use(markdownImSize)
         .use(linenumbers)

app/pages/markdown-it-github-alerts-compat.js

@@ -0,0 +1,79 @@
+// Compatibility wrapper for legacy webpack parser (Next 7 / webpack 4).
+// Adapted from markdown-it-github-alerts (MIT):
+// https://github.com/antfu/markdown-it-github-alerts
+const DEFAULT_GITHUB_ICONS = {
+  note: '<svg class="octicon octicon-info mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M0 8a8 8 0 1 1 16 0A8 8 0 0 1 0 8Zm8-6.5a6.5 6.5 0 1 0 0 13 6.5 6.5 0 0 0 0-13ZM6.5 7.75A.75.75 0 0 1 7.25 7h1a.75.75 0 0 1 .75.75v2.75h.25a.75.75 0 0 1 0 1.5h-2a.75.75 0 0 1 0-1.5h.25v-2h-.25a.75.75 0 0 1-.75-.75ZM8 6a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z"></path></svg>',
+  tip: '<svg class="octicon octicon-light-bulb mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M8 1.5c-2.363 0-4 1.69-4 3.75 0 .984.424 1.625.984 2.304l.214.253c.223.264.47.556.673.848.284.411.537.896.621 1.49a.75.75 0 0 1-1.484.211c-.04-.282-.163-.547-.37-.847a8.456 8.456 0 0 0-.542-.68c-.084-.1-.173-.205-.268-.32C3.201 7.75 2.5 6.766 2.5 5.25 2.5 2.31 4.863 0 8 0s5.5 2.31 5.5 5.25c0 1.516-.701 2.5-1.328 3.259-.095.115-.184.22-.268.319-.207.245-.383.453-.541.681-.208.3-.33.565-.37.847a.751.751 0 0 1-1.485-.212c.084-.593.337-1.078.621-1.489.203-.292.45-.584.673-.848.075-.088.147-.173.213-.253.561-.679.985-1.32.985-2.304 0-2.06-1.637-3.75-4-3.75ZM5.75 12h4.5a.75.75 0 0 1 0 1.5h-4.5a.75.75 0 0 1 0-1.5ZM6 15.25a.75.75 0 0 1 .75-.75h2.5a.75.75 0 0 1 0 1.5h-2.5a.75.75 0 0 1-.75-.75Z"></path></svg>',
+  important: '<svg class="octicon octicon-report mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M0 1.75C0 .784.784 0 1.75 0h12.5C15.216 0 16 .784 16 1.75v9.5A1.75 1.75 0 0 1 14.25 13H8.06l-2.573 2.573A1.458 1.458 0 0 1 3 14.543V13H1.75A1.75 1.75 0 0 1 0 11.25Zm1.75-.25a.25.25 0 0 0-.25.25v9.5c0 .138.112.25.25.25h2a.75.75 0 0 1 .75.75v2.19l2.72-2.72a.749.749 0 0 1 .53-.22h6.5a.25.25 0 0 0 .25-.25v-9.5a.25.25 0 0 0-.25-.25Zm7 2.25v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 9a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z"></path></svg>',
+  warning: '<svg class="octicon octicon-alert mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M6.457 1.047c.659-1.234 2.427-1.234 3.086 0l6.082 11.378A1.75 1.75 0 0 1 14.082 15H1.918a1.75 1.75 0 0 1-1.543-2.575Zm1.763.707a.25.25 0 0 0-.44 0L1.698 13.132a.25.25 0 0 0 .22.368h12.164a.25.25 0 0 0 .22-.368Zm.53 3.996v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 11a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z"></path></svg>',
+  caution: '<svg class="octicon octicon-stop mr-2" viewBox="0 0 16 16" version="1.1" width="16" height="16" aria-hidden="true"><path d="M4.47.22A.749.749 0 0 1 5 0h6c.199 0 .389.079.53.22l4.25 4.25c.141.14.22.331.22.53v6a.749.749 0 0 1-.22.53l-4.25 4.25A.749.749 0 0 1 11 16H5a.749.749 0 0 1-.53-.22L.22 11.53A.749.749 0 0 1 0 11V5c0-.199.079-.389.22-.53Zm.84 1.28L1.5 5.31v5.38l3.81 3.81h5.38l3.81-3.81V5.31L10.69 1.5ZM8 4a.75.75 0 0 1 .75.75v3.5a.75.75 0 0 1-1.5 0v-3.5A.75.75 0 0 1 8 4Zm0 8a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z"></path></svg>'
+}
+
+function capitalize(str) {
+  return str.charAt(0).toUpperCase() + str.slice(1)
+}
+
+export default function markdownItGitHubAlerts(md, options = {}) {
+  const markers = options.markers || ['TIP', 'NOTE', 'IMPORTANT', 'WARNING', 'CAUTION']
+  const icons = options.icons || DEFAULT_GITHUB_ICONS
+  const matchCaseSensitive = options.matchCaseSensitive || false
+  const titles = options.titles || {}
+  const classPrefix = options.classPrefix || 'markdown-alert'
+
+  const markerNameRE = markers === '*' ? '\\w+' : markers.join('|')
+  const RE = new RegExp(
+    `^\\\\?\\[\\!(${markerNameRE})\\]([^\\n\\r]*)`,
+    matchCaseSensitive ? '' : 'i'
+  )
+
+  md.core.ruler.after('block', 'github-alerts', (state) => {
+    const tokens = state.tokens
+    for (let i = 0; i < tokens.length; i++) {
+      if (tokens[i].type !== 'blockquote_open') {
+        continue
+      }
+
+      const open = tokens[i]
+      const startIndex = i
+      while (i <= tokens.length && (!tokens[i] || tokens[i].type !== 'blockquote_close')) {
+        i += 1
+      }
+
+      const close = tokens[i]
+      const endIndex = i
+      const firstContent = tokens
+        .slice(startIndex, endIndex + 1)
+        .find((token) => token.type === 'inline')
+      if (!firstContent) {
+        continue
+      }
+
+      const match = firstContent.content.match(RE)
+      if (!match) {
+        continue
+      }
+
+      const type = match[1].toLowerCase()
+      const title = match[2].trim() || (
+        Object.prototype.hasOwnProperty.call(titles, type)
+          ? titles[type]
+          : capitalize(type)
+      )
+      const icon = Object.prototype.hasOwnProperty.call(icons, type) ? icons[type] : ''
+
+      firstContent.content = firstContent.content.slice(match[0].length).trimStart()
+
+      open.type = 'alert_open'
+      open.tag = 'div'
+      open.meta = { title, type, icon }
+
+      close.type = 'alert_close'
+      close.tag = 'div'
+    }
+  })
+
+  md.renderer.rules.alert_open = function(tokens, idx) {
+    const { title, type, icon } = tokens[idx].meta
+    return `<div class="${classPrefix} ${classPrefix}-${type}"><p class="${classPrefix}-title">${icon}${title}</p>`
+  }
+}

package.json

@@ -23,6 +23,7 @@
     "markdown-it-deflist": "^2.0.3",
     "markdown-it-emoji": "^1.4.0",
     "markdown-it-footnote": "^3.0.1",
+    "markdown-it-github-alerts": "0.1.2",
     "markdown-it-task-lists": "^2.1.1",
     "markdown-it-toc-done-right": "^4.0.1",
     "md-it-meta": "^0.0.2",

yarn.lock

@@ -3589,6 +3589,11 @@ markdown-it-footnote@^3.0.1:
   resolved "https://registry.yarnpkg.com/markdown-it-footnote/-/markdown-it-footnote-3.0.3.tgz#e0e4c0d67390a4c5f0c75f73be605c7c190ca4d8"
   integrity sha512-YZMSuCGVZAjzKMn+xqIco9d1cLGxbELHZ9do/TSYVzraooV8ypsppKNmUJ0fVH5ljkCInQAtFpm8Rb3eXSrt5w==
 
+markdown-it-github-alerts@0.1.2:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/markdown-it-github-alerts/-/markdown-it-github-alerts-0.1.2.tgz#b2f858756535b78bdce9128ffe0114b1875d469f"
+  integrity sha512-jtCrfFxXR6c/bNRBvWkoqUquEDdIF9q7/gNZjP47W96kaIiBMiYHbpf468IPeZJB5BVRls6+IXGchhQSTxy0DQ==
+
 markdown-it-task-lists@^2.1.1:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/markdown-it-task-lists/-/markdown-it-task-lists-2.1.1.tgz#f68f4d2ac2bad5a2c373ba93081a1a6848417088"