Build: Fix the ESLint config for demos

The ESLint config for `demos` extends the one for the `ui` directory. However,
the `ui` one used to not be a root one, making the `demos` one effectively not
depend on the `jquery` preset. Fix that and fix lots of lint violations in
`demos/search.js`.

Closes gh-2303

demos/.eslintrc.json

@@ -1,5 +1,9 @@
 {
 	"root": true,
 
-	"extends": "../ui/.eslintrc.json"
+	"extends": "../ui/.eslintrc.json",
+
+	"globals": {
+		"require": true
+	}
 }

demos/search.js

@@ -596,32 +596,32 @@
 		return result;
 	}
 	$.ajaxTransport( "json", function( options, originalOptions ) {
-		if ( options.url.indexOf( 'search.json' ) === -1 ) {
+		if ( options.url.indexOf( "search.json" ) === -1 ) {
 			return;
 		}
 		return {
 			abort: function() {},
 			send: function( headers, completeCallback ) {
-				console.log( 'Mocked AJAX response for ' + options.url );
+				console.log( "Mocked AJAX response for " + options.url );
-				var result = searchResponse( originalOptions.data.term || '' );
+				var result = searchResponse( originalOptions.data.term || "" );
 				setTimeout( function() {
-					completeCallback( 200, 'OK', { text: JSON.stringify( result ) }, [] );
+					completeCallback( 200, "OK", { text: JSON.stringify( result ) }, [] );
 				}, 2000 );
 			}
 		};
 	} );
 	$.ajaxTransport( "script", function( options, originalOptions ) {
-		if ( options.url.indexOf( 'search.json' ) === -1 ) {
+		if ( options.url.indexOf( "search.json" ) === -1 ) {
 			return;
 		}
 		return {
 			abort: function() {},
 			send: function( headers, completeCallback ) {
-				console.log( 'Mocked AJAX response for ' + options.url );
+				console.log( "Mocked AJAX response for " + options.url );
-				var result = searchResponse( originalOptions.data.term || '' );
+				var result = searchResponse( originalOptions.data.term || "" );
-				var script = options.jsonpCallback + '(' + JSON.stringify( result ) + ')';
+				var script = options.jsonpCallback + "(" + JSON.stringify( result ) + ")";
 				setTimeout( function() {
-					completeCallback( 200, 'OK', { text: script }, [] );
+					completeCallback( 200, "OK", { text: script }, [] );
 				}, 2000 );
 			}
 		};

ui/.eslintrc.json

@@ -1,4 +1,8 @@
 {
+	"root": true,
+
+	"extends": "jquery",
+
 	"parserOptions": {
 		"ecmaVersion": 5
 	},