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103 lines
2.8 KiB
Markdown
103 lines
2.8 KiB
Markdown
# Updating Charts
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It's pretty common to want to update charts after they've been created. When the chart data or options are changed, Chart.js will animate to the new data values and options.
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## Adding or Removing Data
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Adding and removing data is supported by changing the data array. To add data, just add data into the data array as seen in this example.
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```javascript
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function addData(chart, label, data) {
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chart.data.labels.push(label);
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chart.data.datasets.forEach((dataset) => {
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dataset.data.push(data);
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});
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chart.update();
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}
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function removeData(chart) {
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chart.data.labels.pop();
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chart.data.datasets.forEach((dataset) => {
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dataset.data.pop();
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});
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chart.update();
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}
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```
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## Updating Options
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To update the options, mutating the options property in place or passing in a new options object are supported.
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- If the options are mutated in place, other option properties would be preserved, including those calculated by Chart.js.
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- If created as a new object, it would be like creating a new chart with the options - old options would be discarded.
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```javascript
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function updateConfigByMutating(chart) {
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chart.options.plugins.title.text = 'new title';
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chart.update();
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}
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function updateConfigAsNewObject(chart) {
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chart.options = {
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responsive: true,
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plugins: {
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title: {
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display: true,
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text: 'Chart.js'
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}
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},
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scales: {
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x: {
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display: true
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},
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y: {
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display: true
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}
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}
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};
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chart.update();
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}
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```
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Scales can be updated separately without changing other options.
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To update the scales, pass in an object containing all the customization including those unchanged ones.
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Variables referencing any one from `chart.scales` would be lost after updating scales with a new `id` or the changed `type`.
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```javascript
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function updateScales(chart) {
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let xScale = chart.scales.x;
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let yScale = chart.scales.y;
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chart.options.scales = {
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newId: {
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display: true
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},
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y: {
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display: true,
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type: 'logarithmic'
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}
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};
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chart.update();
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// need to update the reference
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xScale = chart.scales.newId;
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yScale = chart.scales.y;
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}
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```
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You can also update a specific scale either by its id.
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```javascript
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function updateScale(chart) {
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chart.options.scales.y = {
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type: 'logarithmic'
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};
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chart.update();
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}
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```
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Code sample for updating options can be found in [toggle-scale-type.html](https://www.chartjs.org/samples/latest/scales/toggle-scale-type.html).
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## Preventing Animations
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Sometimes when a chart updates, you may not want an animation. To achieve this you can call `update` with `'none'` as mode.
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