ohadinho ohadinho - 6 months ago 324
jQuery Question

Uncaught TypeError: Cannot read property 'offsetWidth' of undefined - chart.js

I have this simple html:

<canvas id="myChart" width="400" height="400"></canvas>


and this js:

var ctx = document.getElementById("myChart");

var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero: true
}
}]
}
}
});


Even though the canvas is configured with
myChart
id, I get the following error:

Uncaught TypeError: Cannot read property 'offsetWidth' of undefined


JSFiddle:
https://jsfiddle.net/kroejrhx/

Answer

You need ctx to contain the canvas' context, not the canvas element itself.

Try var ctx = document.getElementById("myChart").getContext("2d");

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