#Custom interaction events

Write JS in the events editor and register interactions via the ECharts instance chart to enable linkage, such as navigating to a new page or opening a drill-down dialog.

#Register and Unregister

• Register: chart.on(eventName, handler)
• Unregister: chart.off(eventName, handler) or chart.off(eventName) to clear events by name

Note: For safety, it's strongly recommended to unregister an event before registering it again!

#Handler params structure

Common fields include params.data and params.name.

#Example: click to highlight selection

chart.off('click');
chart.on('click', (params) => {
  const { seriesIndex, dataIndex } = params;
  // Highlight the current data point
  chart.dispatchAction({ type: 'highlight', seriesIndex, dataIndex });
  // Downplay others
  chart.dispatchAction({ type: 'downplay', seriesIndex });
});

#Example: click to navigate

chart.off('click');
chart.on('click', (params) => {
  const order_date = params.data[0]
  
  // Option 1: internal navigation without full page refresh (recommended), only need relative path
  ctx.router.navigate(`/new-path/orders?order_date=${order_date}`)

  // Option 2: navigate to external page, full URL required
  window.location.href = `https://www.host.com/new-path/orders?order_date=${order_date}`

  // Option 3: open external page in a new tab, full URL required
  window.open(`https://www.host.com/new-path/orders?order_date=${order_date}`)
});

#Example: click to open details dialog (drill-down)

chart.off('click');
chart.on('click', (params) => {
  ctx.openView(ctx.model.uid + '-1', {
    mode: 'dialog',
    size: 'large',
    defineProperties: {}, // register context variables for the new dialog
  });
});

In the newly opened dialog, use chart context variables via ctx.view.inputArgs.XXX.

#Preview and Save

• Click "Preview" to load and execute the event code.
• Click "Save" to persist the current event configuration.
• Click "Cancel" to revert to the last saved state.

Recommendations:

• Always use chart.off('event') before binding to avoid duplicate executions or increased memory usage.
• Use lightweight operations (e.g., dispatchAction, setOption) inside event handlers to avoid blocking the rendering process.
• Validate against chart options and data queries to ensure that the fields handled in the event are consistent with the current data.