Hands-On Data Structures and Algorithms with JavaScript

Enabling web worker communications

Now that the app component is set and ready to send messages, the worker needs to be enabled to receive the messages from the main thread. To do that, add the following code to your worker.js file:

init();function init() {   self.addEventListener('message', function(e) {      var code = e.data;      if(typeof code !== 'string' || code.match(/.*[a-zA-Z]+.*/g)) {         respond('Error! Cannot evaluate complex expressions yet. Please try         again later');      } else {         respond(evaluate(convert(code)));      }   });}

As you can see, we added the capability of listening for any message that might be sent to the worker and then the worker simply takes that data and applies some basic validation on it before trying to evaluate and return any value ...