[英]Real time chart using pusher and canvas js
<script type="text/javascript">
window.onload = function () {
// initial values of dataPoints
var dps = [
{label: "Management Wing", y: 125} ,
{label: "Production Lab", y: 332},
{label: "Cafeteria", y: 55},
{label: "Library", y: 46},
{label: "Recreation Centre", y: 32}
];
var totalEmployees = "total people on campus: 590";
var chart = new CanvasJS.Chart("chartContainer",{
theme: "theme2",
title:{
text: "People On Campus"
},
axisY: {
title: "Number of People"
},
legend:{
verticalAlign: "top",
horizontalAlign: "centre",
fontSize: 18
},
data : [{
type: "column",
showInLegend: true,
legendMarkerType: "none",
legendText: totalEmployees,
indexLabel: "{y}",
dataPoints: dps
}]
});
// renders initial chart
chart.render();
var sum = 590; //initial sum
var updateInterval = 1000; // milliseconds
var updateChart = function () {
// Selecting a random dataPoint
var dataPointIndex = Math.round(Math.random()*4);
// generating random value
var deltaY = Math.round(2 + Math.random() *(-2-2));
// adding random value to random dataPoint
dps[dataPointIndex].y = (dps[dataPointIndex].y + deltaY) > 0 ? dps[dataPointIndex].y + deltaY : 0 ;
// updating legend text.
sum = sum + deltaY;
totalEmployees = "total people on campus: " + sum;
chart.options.data[0].legendText = totalEmployees;
chart.render();
};
// update chart after specified interval
setInterval(function(){updateChart()}, updateInterval);
}
</script>
<script type="text/javascript" src="/assets/script/canvasjs.min.js"></script>
</head>
嗨,我正在使用canvasjs.com 。 在上面的代碼中,我如何訪問label的值。 我將y的值作為JSON.stringify(dps[0].name)
- 它返回Management Wing
125值。 但我需要實現像management wing
, production lab
這樣的標簽。這樣我就可以跟蹤推送事件觸發時應該更新哪個標簽。
你必須使用ajax。 在updateChart上插入一個ajax,看看這里
// global variable label n y
var labelJSON = [];
var yJSON = [];
var updateChart = function () {
$.getJSON("http://www.domain.com/data/json", function(json){
for(var i=0; i<json.length; i++) {
labelJSON[i] = json[i].label
yJSON[i] = json[i].y;
}
});
for (var i = 0; i < dps.length; i++) {
// update chart here
dps[i] = {label: labelJSON[i] , y: yJSON[i]};
};
chart.render();
};
http://www.domain.com/data/json的URL提供的輸出就像你在var dps上的數據一樣。
並且不要忘記在canvasjs.min.js上加載jquery庫。 所以看起來像這里
<script type="text/javascript" src="/assets/script/jquery.min.js"></script
<script type="text/javascript" src="/assets/script/canvasjs.min.js"></script>
我希望它有用
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