RGraph: HTML5 Javascript charts library - Adjusting your charts interactively - Thermometer chart

Nothing pertinent is kept in the registry. If you wish to get the new value of the thermometer you can check obj.value. If you want the value before the adjustment, you can check the value with the onadjustbegin event (instead of the onadjustend event).

<script>
    window.onload = function (e)
    {
        var thermometer = new RGraph.Thermometer('myc', 0, 100, 78);
        
        var grad = thermometer.context.createLinearGradient(0,50,0,350);
        grad.addColorStop(0, 'orange');
        grad.addColorStop(1, 'white');

        thermometer.Set('chart.colors', [grad]);
        thermometer.Set('chart.title.side', 'An adjustable thermometer');
        thermometer.Set('chart.adjustable', true);
        thermometer.Draw();

        RGraph.AddCustomEventListener(thermometer, 'onadjustbegin', function (obj) {document.getElementById("output").value += 'Value before adjustment: ' + obj.value + '\n';});
        RGraph.AddCustomEventListener(thermometer, 'onadjust', function (obj) {document.getElementById("output").value += 'Value during adjustment: ' + obj.value + '\n';});
        RGraph.AddCustomEventListener(thermometer, 'onadjustend', function (obj) {document.getElementById("output").value += 'Value after adjustment: ' + obj.value + '\n';});
    }
</script>