限制听众在设定时间内可以触发的次数？

Question

Following on from a question I had yesterday:

Google Directions Service w/ Waypoints returning ZERO_RESULTS

Dr. Molle said that the directions_changed listener would fire again. They were correct. It's firing infinitely. I'm wondering if there's a better place to put this listener, OR if there's a way to limit the amount of times it's allowed to fire in a set period of time.

function route(waypoint) {

distance = 5;   // Default distance

if(waypoint){

    var request = {
        origin: document.getElementById("search-input-from").value,
        destination: document.getElementById("search-input-to").value,
        waypoints: waypoint,
        optimizeWaypoints: true,
        travelMode: google.maps.DirectionsTravelMode.DRIVING
    };
}
else{

    var request = {
        origin: document.getElementById("search-input-from").value,
        destination: document.getElementById("search-input-to").value,
        travelMode: google.maps.DirectionsTravelMode.DRIVING
    };
}

var directionRendererOptions = { draggable: true };

// Make the directions request
directionService.route(request, function(result, status) {
    if (status == google.maps.DirectionsStatus.OK) {

        directionsDisplay.setOptions(directionRendererOptions); 
        directionsDisplay.setDirections(result);
        directionsDisplay.setMap(map);

        var path = result.routes[0].overview_path;

        // more code here that won't matter
    }
    else {
            alert("Directions query failed: " + status);
        }

     //listener for dragged route/polyline

google.maps.event.addListener(directionsDisplay, 'directions_changed', function(){

            var waypoints = directionsDisplay.getDirections().routes[0].legs[0].via_waypoints||[];

            for(var i=0;i<waypoints.length;++i){

               waypoints[i]={stopover:true,location: waypoints[i]}
            }

            route(waypoints);

        });
    });
 }

EDIT: Should explain myself better. Basically as I'm trying to redraw the route, I'm getting an infinite loop of directions_changed .

Also, for anyone looking at this question, I really don't think the downvote was necessary. I didn't lack research or effort, the waypoints part of the documentation is terrible, and in no example did they attempt to use waypoints via LatLng objects. They only used locations.

Answer 1

When you call route(waypoint), set a flag. When the directions_handler function runs, clear the flag, don't re-render the directions.

  var directionsRedraw = false;

  google.maps.event.addListener(directionsDisplay, 'directions_changed', function(){
    if (directionsRedraw == false) {
      directionsRedraw = true;
      var waypoints = directionsDisplay.getDirections().routes[0].legs[0].via_waypoints||[];
      for(var i=0;i<waypoints.length;++i){
        waypoints[i]={stopover:true,location: waypoints[i]}
      }
      route(waypoints);
    } else { 
      directionsRedraw = false;
    }
  });