javascript - About the size of chartjs table

Question

The tables I create always have nothing to do with the custom canvas size

//html
<canvas id="chartTest" width="300" height="300"></canvas>

//js(这就是官网的示例)
var ctx = $('#chartTest')[0].getContext('2d');
var chart = 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
                        }
                    }]
                }
            }
        })

The chart is displayed, but the attributes are like this:

The width and height of the canvas have nothing to do with my customization
May I ask where I went wrong?

Answer 1

Instructions from the official documentation:

// Any of the following formats may be used
var ctx = document.getElementById("myChart");
var ctx = document.getElementById("myChart").getContext("2d");
var ctx = $("#myChart");
var ctx = "myChart";

It does not say that the canvas definition method is var ctx = $('#chartTest')[0].getContext('2d'). Try changing the first line var ctx = $('#chartTest' )[0].getContext('2d') changed to var ctx = document.getElementById('charTest').

Update

See: http://www.chartjs.org/docs/l...

Width and height detection cannot be obtained directly from canvas. You need to nest a p externally and set the p style:

#chart-wrapper {
    position: relative; // 这个必须要有，否则里面会生成的iframe绝对定位，会以外层第一个有定位的元素的坐标系为准
    width: 400px;
    height: 400px;
}

html:

<p id="chart-wrapper">
    <canvas id="myChart"></canvas>
</p>