Since while I cannot set the value of an input field with type=text. Before, I always used something like this:
<input style="display: none" type="text" name="geo_poi" value="" id="geofeld" />
Then, in JavaScript i added code containing a line like this:
document.getElementById("geofeld").value = geo_poi;
This always worked. Maybe the new browsers don't want to support the method above anymore.
So using the following method for setting attributes worked fine.
document.getElementById("geofeld").setAttribute("value", geo_poi);