Port context/layout.js to TypeScript (#51241)

Author: Peter Bengtsson

src/frame/middleware/context/layout.js

@@ -0,0 +1,24 @@
+import type { Response, NextFunction } from 'express'
+
+import type { ExtendedRequest } from '@/types'
+
+export default function layoutContext(req: ExtendedRequest, res: Response, next: NextFunction) {
+  if (!req.context) throw new Error('request is not contextualized')
+  if (!req.context.page) return next()
+
+  let layoutName = 'default'
+  if (req.context.page.layout) {
+    if (typeof req.context.page.layout === 'boolean') {
+      // A `layout: false` value means use no layout.
+      layoutName = ''
+    } else if (typeof req.context.page.layout === 'string') {
+      layoutName = req.context.page.layout
+    } else {
+      throw new Error(`Invalid layout value type: ${req.context.page.layout}`)
+    }
+  }
+
+  req.context.currentLayoutName = layoutName
+
+  return next()
+}

src/frame/middleware/context/layout.ts

@@ -39,7 +39,7 @@ import triggerError from '@/observability/middleware/trigger-error'
 import secretScanning from '@/secret-scanning/middleware/secret-scanning'
 import ghesReleaseNotes from '@/release-notes/middleware/ghes-release-notes'
 import whatsNewChangelog from './context/whats-new-changelog'
-import layout from './context/layout.js'
+import layout from './context/layout'
 import currentProductTree from './context/current-product-tree.js'
 import genericToc from './context/generic-toc.js'
 import breadcrumbs from './context/breadcrumbs.js'

src/frame/middleware/index.ts

@@ -82,6 +82,7 @@ export type Context = {
   autotitleLanguage?: string
   latestPatch?: string
   latestRelease?: string
+  currentLayoutName?: string
 }
 
 export type GHESRelease = {
@@ -185,6 +186,7 @@ export type Page = {
   versions: FrontmatterVersions
   applicableVersions: string[]
   changelog?: ChangeLog
+  layout?: string | boolean
 }
 
 type ChangeLog = {