Dynamic chart with CanvasJs doesn't get update while reading from a file
Question
I've been trying to get a dynamic chart working with CanvasJs. I have a file that gets updated (by another program) and I would like to update my chart each time I have a new record.
I've seen this example (last chart) and I tried to do the same but I'm actually reading from a file.
Here is my code :
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript" src="https://canvasjs.com/assets/script/jquery-1.11.1.min.js"></script>
<script type="text/javascript" src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
<script type="text/javascript">
window.onload = function () {
var dps = [{x: new Date(2017, 04, 20, 07, 20, 00 ), y: 30}]; //dataPoints.
var chart = new CanvasJS.Chart("chartContainer",{
title:{
text: " Cooling Machine Status "
},
axisX:{
valueFormatString: "DD-MM-YY HH:mm:ss" ,
labelAngle: -50
},
axisY:{
title: "Cooling Temperature (F)"
},
data: [{
type: "line",
showInLegend: true,
name: "Temperature",
dataPoints : dps
}]
});
chart.render();
var updateChart = function () {
var rawFile = new XMLHttpRequest();
rawFile.open("GET","/analyticResults/coolingMachine.csv", true);
rawFile.onreadystatechange = function ()
{
if(rawFile.readyState === 4)
{
if(rawFile.status === 200 || rawFile.status == 0)
{
var dps = csvLines = points = [];
csvLines = rawFile.responseText.split(/[\r?\n|\r|\n]+/);
for (var i = 0; i < csvLines.length; i++)
if (csvLines[i].length > 0) {
points = csvLines[i].split(",");
var dateTime = points[0].split(" ");//dateTime[0] = date, dateTime[1] = time
var date = dateTime[0].split("-");
var time = dateTime[1].split(":");
dps.push({
x: new Date(date[2], date[1], date[0], time[0], time[1], time[2]),
y: parseFloat(points[1])
});
}
}
}
};
rawFile.send(null);
if (dps.length > 10 )
{
dps.shift();
}
chart.render();
};
setInterval(function(){updateChart()}, 1000);
}
</script>
<script type="text/javascript" src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
</head>
<body>
<div id="chartContainer" style="height: 300px; width: 70%;">
</div>
</body>
</html>
When I debug the javascript I can see that the values are getting pushed in dps but the chart is not updating...
Did I miss someting ?
Thank you for your time
1 answers
solution1
3 ACCPTED 2017-08-04 05:40:24
You are passing dps to chart-dataPoints. But at the same time you are pushing dps that is declared locally within updateChart method. Removing dps declaration within updateChart method should work in your case.
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