title: How to listen for data changes at more than a particular location in Firebase?
body: <p>I am using Firebase as real-time DB for mobile APP I'm developing (JS Web SDK), the structure is as below in the screenshot, the key = email, each key have the mobile user information, and GPS coordination of the mobile location inside node = "path"  </p>
  
  <p>How to listen on all the the "path" of all the emails (users)? </p>
  
  <p><a href="https://i.stack.imgur.com/8kBYN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/8kBYN.png" alt="enter image description here"></a></p>