A Fuel chart fetching its reading via AJAX

Note: For security reasons the AJAX demos don't work offline. You can view the demos on the RGraph website here: https://www.rgraph.net/demos/index.html

[No canvas support]

This goes in the documents header:
<script src="RGraph.common.core.js"></script>
<script src="RGraph.fuel.js"></script>
Put this where you want the chart to show up:
<canvas id="cvs" width="200" height="200">
    [No canvas support]
This is the code that generates the chart:
    RGraph.AJAX.getNumber('/getdata.html', drawFuel);

    function drawFuel (num)
        var fuel = new RGraph.Fuel({
            id: 'cvs',
            min: 0,
            max: 100,
            value: num,
            options: {