How to put JavaScript values as hidden form fields?

Question

I have a google map that has a marker which is dragged. When I get the new latitude and longitude coordinates, I need to put them into an HTML form as hidden fields.

How can I do that? The example page with current code is here: http://www.comehike.com/outdoors/parks/add_trailhead.php

Answer 1

如果您的表单已经包含隐藏的输入字段，并且这些字段具有ID，则可以执行

document.getElementById("id of the input field").value = myVariable;

Answer 2

Add these to your form (if they dont exist):

<input type="hidden" value="" id="lat" name="lat" />
<input type="hidden" value="" id="lng" name="lng" />

Then once you want to update the values just do:

document.getElementById("lat").setAttribute("value", newLat);
document.getElementById("lng").setAttribute("value", newLng);