I have this code I have made out of a composition of my own code and the template code of Canvasjs which uses API of Canvasjs to make the chart.
Everything is good, I debugged it nicely and the chart shows with my database data as a source. My database data reads the data from a textfile which has data from a Arduino-based Pulse Sensor.
This is my code:
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.4/jquery.min.js"> </script>
<script type="text/javascript">
$().ready(function () {
var dataPoints = [];
var chart = new CanvasJS.Chart("chartContainer",{
title :{
text: "Patient #01"
},
data: [{
type: "line",
dataPoints: dataPoints
}]
});
function updateChart( result ) { // move it here!!!
$.getJSON("arduino_data.php", function( result ){
var dataLength = 40; // number of dataPoints visible at any point
var updateInterval = 20;
var chart = new CanvasJS.Chart("chartContainer",{ // new chart Object
title :{
text: "Patient #01"
},
data: [{
type: "line",
dataPoints: dataPoints
}]
});
for (var i = 0; i <= result.length - 1; i++) {
dataPoints.push({ x: Number(result[i].x), y: Number(result[i].y) });
}
if (dataPoints.length > dataLength){
dataPoints.shift();
}
chart.render();
});
}
// First read - Start
updateChart();
// Update chart after specified time.
setInterval(updateChart, updateInterval);
});
</script>
<script type="text/javascript" src="canvasjs.min.js"></script>
</head>
<body>
<div id="chartContainer" style="height: 300px; width:100%;">
</div>
</body>
</html>
Why do dataLength = 40; and updateInterval=20 and the last line: updateChart();
do not work? Should there be something in updateChart() like updateChart(dataPoints) ??
Why is my chart not live, though I have the right code parts?
EDIT
This is the template code that works without database data. And this is a Live Chart. It updates every second or so.
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.4/jquery.min.js"> </script>
<script type="text/javascript">
window.onload = function () {
var dps = []; // dataPoints
var chart = new CanvasJS.Chart("chartContainer2",{
title :{
text: "Patient #01"
},
data: [{
type: "line",
dataPoints: dps
}]
});
var xVal = 0;
var yVal = 100;
var updateInterval = 20;
var dataLength = 500; // number of dataPoints visible at any point
var updateChart = function (count) {
count = count || 1;
// count is number of times loop runs to generate random dataPoints.
for (var j = 0; j < count; j++) {
yVal = yVal + Math.round(5 + Math.random() *(-5-5));
dps.push({
x: xVal,
y: yVal
});
xVal++;
};
if (dps.length > dataLength)
{
dps.shift();
}
chart.render();
};
// generates first set of dataPoints
updateChart(dataLength);
// update chart after specified time.
setInterval(function(){updateChart()}, updateInterval);
}
</script>
<script type="text/javascript" src="canvasjs.min.js"></script>
As you can see, it is just like my code. However this uses math.randomize data instead of real data from database.
My Question: Why won't my chart keep updating (live) so it will show changes? My chart remains static. I have to refresh it manually to show new data transmission.