Update index.js to support worker environment

src/index.js

@@ -4,6 +4,12 @@ var util = require('util');
 var Blocks = require('./engine/blocks');
 var Runtime = require('./engine/runtime');
 
+/**
+ * Whether the environment is a WebWorker.
+ * @const{boolean}
+ */
+var ENV_WORKER = typeof importScripts === 'function';
+
 /**
  * Handles connections between blocks, stage, and extensions.
  *
@@ -30,6 +36,55 @@ function VirtualMachine () {
     );
 }
 
+/*
+ * Worker Handlers
+ */
+if (ENV_WORKER) {
+    self.vmInstance = new VirtualMachine();
+    self.onmessage = function (e) {
+        var messageData = e.data;
+        switch (messageData.method) {
+        case 'start':
+            self.vmInstance.runtime.start();
+            break;
+        case 'greenFlag':
+            self.vmInstance.runtime.greenFlag();
+            break;
+        case 'stopAll':
+            self.vmInstance.runtime.stopAll();
+            break;
+        case 'blockListener':
+            self.vmInstance.blockListener(messageData.args);
+            break;
+        case 'flyoutBlockListener':
+            self.vmInstance.flyoutBlockListener(messageData.args);
+            break;
+        case 'getPlaygroundData':
+            self.postMessage({
+                method: 'playgroundData',
+                blocks: self.vmInstance.blocks,
+                threads: self.vmInstance.runtime.threads
+            });
+            break;
+        default:
+            throw 'Unknown method' + messageData.method;
+        }
+    };
+    // Bind runtime's emitted events to postmessages.
+    self.vmInstance.runtime.on(Runtime.STACK_GLOW_ON, function (id) {
+        self.postMessage({method: Runtime.STACK_GLOW_ON, id: id});
+    });
+    self.vmInstance.runtime.on(Runtime.STACK_GLOW_OFF, function (id) {
+        self.postMessage({method: Runtime.STACK_GLOW_OFF, id: id});
+    });
+    self.vmInstance.runtime.on(Runtime.BLOCK_GLOW_ON, function (id) {
+        self.postMessage({method: Runtime.BLOCK_GLOW_ON, id: id});
+    });
+    self.vmInstance.runtime.on(Runtime.BLOCK_GLOW_OFF, function (id) {
+        self.postMessage({method: Runtime.BLOCK_GLOW_OFF, id: id});
+    });
+}
+
 /**
  * Inherit from EventEmitter
  */