fix #2443: add parseYoutubeStart() to convert start times (#2447)

* fix #2443: add parseYoutubeStart() to convert start times

* handle null parameter

* add spaces for lint

* switch to regex, handles more cases, simply don't touch unexpected input

* force braces for lint

lib/url.js

@@ -78,6 +78,17 @@ export function parseInternalLinks (href) {
   return {}
 }
 
+export function parseYoutubeStart (t) {
+  // https://stackoverflow.com/questions/17379268/youtube-dropped-t-start-time-support-in-direct-url-and-embed-videos
+  // https://developers.google.com/youtube/player_parameters#start
+  if (!t || !t.match(/^([0-9]+[smh])+$/g)) return t
+  let r = 0
+  for (const m of t.matchAll(/([0-9]+)([smh])/g)) {
+    r += parseInt(m[1]) * Math.pow(60, 'smh'.indexOf(m[2]))
+  }
+  return r.toString()
+}
+
 export function parseEmbedUrl (href) {
   if (!href) return null
 
@@ -132,7 +143,7 @@ export function parseEmbedUrl (href) {
           id: searchParams.get('v'),
           meta: {
             href,
-            start: searchParams.get('t')
+            start: parseYoutubeStart(searchParams.get('t'))
           }
         }
       }
@@ -152,7 +163,7 @@ export function parseEmbedUrl (href) {
         id: pathname.slice(1), // remove leading slash
         meta: {
           href,
-          start: searchParams.get('t')
+          start: parseYoutubeStart(searchParams.get('t'))
         }
       }
     }