Question

I am learning JavaScript and slowly wading my way to understanding why a certain page does not work 🙂

I am doing something like this:

<a onClick="removeAllMarkers(this)" href="#" >Remove All Markers</a>

With the idea that sending this is the correct way to go about things. But I think I don’t really understand the role of “this” in my current situation.

I am getting a JavaScript console error when I press on the link for “clear all markers” on this page:
http://www.comehike.com/outdoors/trees/add_spotted_trees.php?hike_id=108

The page has login credentials: [e-mail] | password

Any ideas what I am fundamentally doing wrong and how is the best way to clear the markers[] array?

I am currently doing something like this:

if (markers)
{
    for (i in markers)
    {
         markers[i].setMap(null);
         markers[i] = null;
    }
}

But that is precisely the part which is having the errors unfortunately. Suggestions? 🙂

Here is the page

Answer 1

Setting an array element to null won’t remove it from the array.

---

To clear an array, either assign the variable to a new empty array:

markers = [];

Or set its length property to 0:

markers.length = 0;

Do this after looping through the array and calling .setMap(null) on each.

---

To only remove only the last item in an array:

markers.pop();