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Changing colour of a polygon overlay in Google Maps dynamically

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Hello forum,

I'm extremely green with Java, and this is actually my first post here. I hope this is the right section for my question.

I'm playing with IOT devices (internet-of-things) and do some remote monitoring. I've been able to get a google maps widget to display different values on the map, like GPS location, temperatures, etc. I would like to add a bit more functionality to this, but not sure how to proceed.

I send my iot data to a company that hosts it, and has various different widgets to display numerical values, simple charts, etc. They have an option where you can write your own code to display whatever you want. The code below takes the average temperature that is uploaded every couple minutes or so, and displays it on the map. Now I've drawn a polygon around the area where the temperatures are being measured, see screenshot. What I would like to do is to have the colour of this polygon change to one of three colours - too hot, turn red. Just right, turn green. Too cold, turn blue.

Is this possible, and could someone give me a nudge in the right direction with the code to get this done?

Thanks in advance,

[Thumbnail for Screenshot-2019-10-23-at-19.52.37.png]
Hein Myb
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So I tried the code below to try and change the fill colour according to what the temperature variable's value is at the time. It doesn't compile. Is it possible to change the fill colour in this way or am I completely off course?

Additionally, in the built-in code editing window supplied by the host it doesn't allow me to use greater than '>'. Its underlined in red and when I hover the pointer over it a message pops up that says '=' expected. Surely this can't be right? Screenshot added.

var pen = new google.maps.Polygon({
   paths: triangleCoords,
   strokeColor: '#F903D0',
   strokeOpacity: 0.8,
   strokeWeight: 2,

   fillColor: '#FA040A',

   if (avgtemp > 25) {
    fillColor: '#27E408'

   if (avgtemp > 35) {
    fillColor: '#FA040A'

   fillOpacity: 0.35

[Thumbnail for Screenshot-2019-10-24-at-07.58.53.png]
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