Question

Can someone tell me why I can’t remove my polylines with this code:

    $("#chkRouteLines").click(function () {

    var polyline = new google.maps.Polyline({
        path: positions,
        strokeColor: "#FF0000",
        strokeOpacity: 1.0,
        strokeWeight: 2,
        visible: true
    }); ;

    if ($(this).is(':checked')) {
        polyline.setMap(map);
    } else {
        polyline.setMap(null);
    }
})

I found in the documentation of google maps api 3 that I need to do: setMap(null)..
But this didn’t work.

Thank you!

Answer 1

You aren’t retaining a reference to the polyline, it is local to the “$(“#chkRouteLines”).click” function. If you have one polyline, make the reference to it global.

var polyline = null; // in the global scope

$("#chkRouteLines").click(function () {
    if (!polyline || !polyline.setMap) {
      polyline = new google.maps.Polyline({
        path: positions,
        strokeColor: "#FF0000",
        strokeOpacity: 1.0,
        strokeWeight: 2,
        visible: true
      }); 
    }

if ($(this).is(':checked')) {
    polyline.setMap(map);
} else {
    polyline.setMap(null);
}

working fiddle

If you need to add and remove multiple different polylines, an array usually works.

code snippet:

var geocoder;
var map;
var polyline;

positions = [new google.maps.LatLng(37.441883,-122.143019),
             new google.maps.LatLng(37.45296,-122.181725)];
function initialize() {
    var map = new google.maps.Map(
    document.getElementById("map_canvas"), {
        center: new google.maps.LatLng(37.4419, -122.1419),
        zoom: 13,
        mapTypeId: google.maps.MapTypeId.ROADMAP
    });
    
    $("#chkRouteLines").click(function () {
        if (!polyline || !polyline.setMap) {
          polyline = new google.maps.Polyline({
            path: positions,
            strokeColor: "#FF0000",
            strokeOpacity: 1.0,
            strokeWeight: 2,
            visible: true
          }); 
        }

    if ($(this).is(':checked')) {
        polyline.setMap(map);
    } else {
        polyline.setMap(null);
    }
})


}
google.maps.event.addDomListener(window, "load", initialize);

html, body, #map_canvas {
    height: 90%;
    width: 100%;
    margin: 0px;
    padding: 0px
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maps.googleapis.com/maps/api/js"></script>
<div id="map_canvas" style="border: 2px solid #3872ac;"></div>
<input id="chkRouteLines" value="click" type="checkbox" />