Maps API v3 Draggable directions with alternate routes

http://stackoverflow.com/questions/41999828

by Arjan Haverkamp

HTML

<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<div id="map-canvas"></div>

CSS

#map-canvas {
  height: 400px;
}

JavaScript

var directionsService = new google.maps.DirectionsService();
var map;

function initialize() {

  var center = new google.maps.LatLng(0, 0);
  var myOptions = {
    zoom: 7,
    mapTypeId: google.maps.MapTypeId.ROADMAP,
    center: center
  }

  map = new google.maps.Map(document.getElementById("map-canvas"), myOptions);

  var start = "Martin Boonlaan 26, Hooglanderveen";
  var end = "Nancy, France";

  plotDirections(start, end);
}

function plotDirections(start, end) {

  var method = 'DRIVING';
  
  var request = {
    origin: start,
    destination: end,
    travelMode: google.maps.DirectionsTravelMode[method],
    provideRouteAlternatives: true
  };

  directionsService.route(request, function(response, status) {

    if (status == google.maps.DirectionsStatus.OK) {

      var routes = response.routes;
      var colors = ['red', 'green', 'blue', 'orange', 'yellow', 'black'];
      var directionsDisplays = [];

      // Reset the start and end variables to the actual coordinates
      start = response.routes[0].legs[0].start_location;
      end = response.routes[0].legs[0].end_location;

			// Loop through each route
      //console.log(routes.length);
      for (var i = 0; i < routes.length; i++) {

        var directionsDisplay = new google.maps.DirectionsRenderer({
          map: map,
          directions: response,
          routeIndex: i,
          draggable: true,
          polylineOptions: {

            strokeColor: colors[i],
            strokeWeight: 4,
            strokeOpacity: .3
          }
        });

        // Push the current renderer to an array
        directionsDisplays.push(directionsDisplay);

        // Listen for the directions_changed event for each route
        google.maps.event.addListener(directionsDisplay, 'directions_changed', (function(directionsDisplay, i) {

          return function() {

            var directions = directionsDisplay.getDirections();
            var new_start =...