Add some whimsical fun with an easter egg

Gruntfile.js

@@ -513,6 +513,8 @@ module.exports = function(grunt) {
 					[ WORKING_DIR + 'wp-admin/js/common.js' ]: [ './src/js/_enqueues/admin/common.js' ],
 					[ WORKING_DIR + 'wp-admin/js/custom-background.js' ]: [ './src/js/_enqueues/admin/custom-background.js' ],
 					[ WORKING_DIR + 'wp-admin/js/custom-header.js' ]: [ './src/js/_enqueues/admin/custom-header.js' ],
+					[ WORKING_DIR + 'wp-admin/js/teletype.js' ]: [ './src/js/_enqueues/admin/teletype.js' ],
+					[ WORKING_DIR + 'wp-admin/js/teletype-loader.js' ]: [ './src/js/_enqueues/admin/teletype-loader.js' ],
 					[ WORKING_DIR + 'wp-admin/js/customize-controls.js' ]: [ './src/js/_enqueues/wp/customize/controls.js' ],
 					[ WORKING_DIR + 'wp-admin/js/customize-nav-menus.js' ]: [ './src/js/_enqueues/wp/customize/nav-menus.js' ],
 					[ WORKING_DIR + 'wp-admin/js/customize-widgets.js' ]: [ './src/js/_enqueues/wp/customize/widgets.js' ],

src/js/_enqueues/admin/teletype-loader.js

@@ -0,0 +1,114 @@
+/**
+ * Hides the admin easter egg behind the command palette.
+ *
+ * No command is registered: a registered command would be listed as soon as its phrase
+ * matched. This listens for Enter while the palette is open instead, so the palette shows
+ * its ordinary "No results found." state throughout.
+ *
+ * The phrase is compared in its Dvorak/QWERTY-substituted form so that it is not a
+ * readable string in the admin bundle.
+ *
+ * @output wp-admin/js/teletype-loader.js
+ */
+
+( function ( wp, settings ) {
+	'use strict';
+
+	if ( ! wp || ! wp.data || ! settings ) {
+		return;
+	}
+
+	var KEY  = 'ishdg;rsdkot',
+		FROM = '\',.pyfgcrl/=\\aoeuidhtns-;qjkxbmwvz"<>PYFGCRL?+|AOEUIDHTNS_:QJKXBMWVZ[]',
+		TO   = 'qwertyuiop[]\\asdfghjkl;\'zxcvbnm,./QWERTYUIOP{}|ASDFGHJKL:"ZXCVBNM<>?-=';
+
+	/**
+	 * Applies the Dvorak/QWERTY substitution cipher.
+	 *
+	 * @param {string} value Text to substitute.
+	 * @return {string} Substituted text.
+	 */
+	function dvortr( value ) {
+		var map = {},
+			i;
+
+		for ( i = 0; i < FROM.length; i++ ) {
+			map[ FROM.charAt( i ) ] = TO.charAt( i );
+		}
+
+		return value.replace( /[\s\S]/g, function ( character ) {
+			return map[ character ] || character;
+		} );
+	}
+
+	/**
+	 * Fetches the payload if it is not already loaded, then plays it.
+	 */
+	function play() {
+		var script;
+
+		if ( wp.teletype ) {
+			wp.teletype.run( settings.name );
+			return;
+		}
+
+		script = document.createElement( 'script' );
+		script.src = settings.src;
+
+		script.onload = function () {
+			if ( wp.teletype ) {
+				wp.teletype.run( settings.name );
+			}
+		};
+
+		document.head.appendChild( script );
+	}
+
+	/**
+	 * Acts on the phrase when it is submitted from an open command palette.
+	 *
+	 * @param {KeyboardEvent} event The keydown event.
+	 */
+	function onKeydown( event ) {
+		var store,
+			input = event.target,
+			value;
+
+		if ( 'Enter' !== event.key || ! input || ! input.value ) {
+			return;
+		}
+
+		store = wp.data.select( 'core/commands' );
+
+		if ( ! store || ! store.isOpen() ) {
+			return;
+		}
+
+		/*
+		 * The palette's search field is a combobox: while any command matches, one of
+		 * them is the active option and Enter belongs to it. Only an empty result list
+		 * is ours to take, otherwise a post that happens to be named for the phrase
+		 * would never open.
+		 */
+		if (
+			'combobox' !== input.getAttribute( 'role' ) ||
+			input.getAttribute( 'aria-activedescendant' )
+		) {
+			return;
+		}
+
+		value = input.value.toLowerCase().replace( /[^a-z0-9]/g, '' );
+
+		if ( ! value || dvortr( value ) !== KEY ) {
+			return;
+		}
+
+		event.preventDefault();
+		event.stopPropagation();
+
+		wp.data.dispatch( 'core/commands' ).close();
+		play();
+	}
+
+	document.addEventListener( 'keydown', onKeydown, true );
+}( window.wp, window.wpTeletype ) );