Support a key sequence for testing the celebration

Since it is not yet April 7th, 2025, the code to turn on the 20th
birthday celebration needs to be tested either by changing the clock, or
by a hack like this: typing the digits `2` and `0` will do it.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

assets/js/application.js

@@ -104,13 +104,26 @@ var BrowserFallbacks = {
 }
 
 var GitTurns20 = {
+  keySequence: '20',
+  keySequenceOffset: 0,
+
   init: function() {
     const today = new Date();
     if (today.getFullYear() === 2025 && today.getMonth() === 3 && today.getDate() === 7) {
       this.celebrate();
     }
   },
 
+  keydown: function(e) {
+    if (this.keySequenceOffset >= this.keySequence.length) return;
+    if (this.keySequence[this.keySequenceOffset] === e.key) {
+      if (++this.keySequenceOffset === this.keySequence.length) {
+        this.celebrate();
+        this.keySequenceOffset = 0;
+      }
+    }
+  },
+
   celebrate: function() {
     document.documentElement.dataset.celebration = 'git-turns-20';
   }
@@ -180,6 +193,7 @@ var Search = {
         e.preventDefault();
         $('form#search input').focus();
       }
+      else if (e.target.tagName.toUpperCase() !== 'INPUT') GitTurns20.keydown(e);
     });
   },