There is a chart instance already initialized on the dom.
时间: 2023-10-19 13:22:39 浏览: 36
To work with an existing chart instance, you can use the `Chart.js` library's `Chart()` constructor and pass in the existing canvas element's context and the chart configuration options. Here is an example:
```javascript
const canvas = document.getElementById('myChart');
const ctx = canvas.getContext('2d');
const chartData = {
labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
datasets: [{
label: 'My Dataset',
data: [10, 20, 30, 40, 50, 60, 70],
backgroundColor: 'rgba(255, 99, 132, 0.2)',
borderColor: 'rgba(255, 99, 132, 1)',
borderWidth: 1
}]
};
const chartOptions = {
responsive: true,
maintainAspectRatio: false
};
const myChart = new Chart(ctx, {
type: 'bar',
data: chartData,
options: chartOptions
});
```
In this example, the canvas element with the ID of `myChart` already exists on the page. We grab the canvas element using `document.getElementById()`. Then, we get the canvas context using `.getContext('2d')`.
Next, we define the chart data and options as usual.
Finally, we create a new instance of the `Chart()` constructor and pass in the canvas context and chart data and options. This will update the existing chart on the canvas element with the new data and options.