title: Javascript check yield support
body: <p>I read about the yield keyword in JavaScript and I need to use it in my project. I read that this keyword has been implemented starting from a certain version of JS so I think that old browsers don't support it (right?).</p>
  
  <p>Is there a way to check if the yield keyword is supported? or at least is there a way to check if the version of JS is greater or equal than the one that implements that keyword (1.7)?</p>