title: What does it mean equal and greater-than sign (=>) in Javascript?
body: <p>In Meteor Whatsapp example project is file where "=>" is used, but my WebStorm IDE detect it as error. I can't find any docs about this syntax.</p>
  
  <pre><code>chats.forEach( chat =&gt; {
    let message = Messages.findOne({ chatId: { $exists: false } });
    chat.lastMessage = message;
    let chatId = Chats.insert(chat);
    Messages.update(message._id, { $set: { chatId: chatId } })
  });
  </code></pre>
  
  <p><a href="https://github.com/idanwe/meteor-whatsapp/blob/master/server/bootstrap.js" rel="nofollow">GitHub repository for bootstrap.js file is here</a></p>
  
  <p>What is "=>" ?</p>