The API for chart.js
allows one to edit points of the datasets loaded into it, for example:
.update( )
Calling update() on your Chart instance will re-render the chart with any updated values, allowing you to edit the value of multiple existing points, then render those in one animated render loop.
.addData( valuesArray, label )
Calling addData(valuesArray, label) on your Chart instance passing an array of values for each dataset, along with a label for those points.
.removeData( )
Calling removeData() on your Chart instance will remove the first value for all datasets on the chart.
All of these are great, but I cannot figure out how to load an entirely new dataset in, wiping out the old. The documentation does not seem to cover this.
Chart. js provides a selection of ready to go charts which can be styled and configured while D3 offers building blocks which are combined to create virtually any data visualisation.
js convention is to call it ctx . An object literal containing the data and the configuration options that Chart. js will use to build your chart. The required properties are type and data . In our example type is 'line' because we want a line chart.
Is it possible to use chart. js for a desktop/mobile application using html that connects through an esp8266 access point or does it need a wifi connection? @marionboynton, CanvasJS is a standalone library that can work offline without any internet connection.
clear() Will clear the chart canvas.
I had huge problems with this
First I tried .clear()
then I tried .destroy()
and I tried setting my chart reference to null
What finally fixed the issue for me: deleting the <canvas>
element and then reappending a new <canvas>
to the parent container
There's a million ways to do this:
var resetCanvas = function () { $('#results-graph').remove(); // this is my <canvas> element $('#graph-container').append('<canvas id="results-graph"><canvas>'); canvas = document.querySelector('#results-graph'); // why use jQuery? ctx = canvas.getContext('2d'); ctx.canvas.width = $('#graph').width(); // resize to parent width ctx.canvas.height = $('#graph').height(); // resize to parent height var x = canvas.width/2; var y = canvas.height/2; ctx.font = '10pt Verdana'; ctx.textAlign = 'center'; ctx.fillText('This text is centered on the canvas', x, y); };
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