title: In leaflet, how to detect whether a LatLng in current display area?
body: <p>As I know, </p>
  
  <pre><code>map.project(latlng)
  </code></pre>
  
  <p>can return a point. However, I've no idea about how to tell whether this point is in the current display area of the map.. </p>
  
  <p>Does anyone have ideas about this?</p>