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Chart Events

Updated on Sep 16, 2026

This article describes the available events for the Telerik Chart for Blazor:

OnAxisLabelClick
OnDragEnd
OnDragStart
OnDrilldown
OnLegendItemClick
OnSeriesClick
OnZoomEnd
OnZoomStart

OnAxisLabelClick

The OnAxisLabelClick event fires when the user clicks a label item on any of the Chart axes. The event argument is of type ChartAxisLabelClickEventArgs and exposes the following properties:

Property	Type	Description
`AxisName`	`string`	The value of the `Name` parameter of the Chart axis. Returns `null` if `Name` is not set.
`Index`	`int`	The label index on the clicked axis.
`Text`	`string`	The visible value of the label. It may be formatted.
`Value`	`object`	The underlying non-formatted value of the label. The `Value` can be: The same as the `Text` value when clicking on a category axis label. A numeric value when clicking on a value axis label. An ISO-8601 DateTime string when clicking on a date axis.

Using the Chart OnAxisLabelClick event

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OnLegendItemClick

The OnLegendItemClick event fires when the user clicks on any item in the Chart legend. The event argument is of type ChartLegendItemClickEventArgs and exposes the following properties:

Property	Type	Description
`PointIndex`	`int?`	The data point index in the series `Data`. Applies to single-series Charts only (Pie and Donut).
`SeriesIndex`	`int`	The series index in the `ChartSeriesItems` collection.
`Text`	`string`	The label of the clicked legend item. In multi-series Charts, the `Text` value matches the `ChartSeries` `Name`. In single-series Charts (Pie and Donut), the `Text` value matches the `CategoryField` value.

Using the Chart OnLegendItemClick event

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OnDragEnd

The Chart OnDragEnd event fires at the end of a drag (pan) gesture. The event argument is of type ChartDragEndEventArgs and exposes the following properties:

Property	Type	Description
`AxisRanges`	`Dictionary<string, ChartAxisRange>`	The visible range of each axis at the end of the drag. The dictionary key is the axis name. Each `ChartAxisRange` value has `Min` and `Max` properties that reflect the new axis range.

The OnDragEnd event fires after OnDragStart.

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OnDragStart

The Chart OnDragStart event fires at the beginning of a drag (pan) gesture. The event argument is of type ChartDragStartEventArgs and exposes the following properties:

Property	Type	Description
`AxisRanges`	`Dictionary<string, ChartAxisRange>`	The visible range of each axis at the start of the drag. The dictionary key is the axis name. Each `ChartAxisRange` value has `Min` and `Max` properties that reflect the current axis range.

The OnDragStart event fires before OnDragEnd.

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The OnDrilldown event is triggered when the drill-down functionality executes. The handler of this event accepts a ChartDrilldownEventArgs object as a parameter. You can access the name of the drilled down (clicked) series through the SeriesName property of the event arguments object.

OnSeriesClick

The OnSeriesClick event fires as a response to the user click on a <ChartSeries>.

Below you can find:

Event Arguments
Examples:

Event Arguments

The event handler receives a ChartSeriesClickEventArgs object which provides the following data:

DataItem - provides the data model of the current series item. You need to cast it to the type from your datasource, which needs to be serializable.
- If you are using a Date Axis, the DataItem will contain the only the aggregated value in the corresponding y-value field, because it is a collection of more than one items. See the Category below for details.
Category - provides information on the category the data point is located in. You need to cast it to the type in your data source, for example DateTime, string, int or another type. The Category parameter is applicable to Categorical Charts.
- When using a Date Axis, you can use it, together with the BaseUnit value of the axis, to filter the data source and obtain the actual data items from the data source in case you want to provide extra information about them.
Percentage - applicable to Donut, Pie and Stacked 100% Charts - the percentage value of the current data point from the whole.
SeriesIndex - provides the index of the <ChartSeries> the data point belongs to.
SeriesName - bound to the Name parameter of the <ChartSeries> the data point belongs to.
SeriesColor - shows the RGB color of the Series the data point belongs to.
CategoryIndex - shows the index of the data point's x-axis category.

Examples

These examples showcase the different applications of the OnSeriesClick event.

Basic Click Handler
Get The Data Model For The Clicked Series
Load Data On Demand Based On Series Click

Property	Type	Description
`AxisRanges`	`Dictionary<string, ChartAxisRange>`	The visible range of each axis at the end of the zoom. The dictionary key is the axis name. Each `ChartAxisRange` value has `Min` and `Max` properties that reflect the new axis range.

The OnZoomEnd event fires after OnZoomStart.

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OnZoomStart

The Chart OnZoomStart event fires at the beginning of a zoom gesture. The event argument is of type ChartZoomStartEventArgs and exposes the following properties:

Property	Type	Description
`AxisRanges`	`Dictionary<string, ChartAxisRange>`	The visible range of each axis at the start of the zoom. The dictionary key is the axis name. Each `ChartAxisRange` value has `Min` and `Max` properties that reflect the current axis range.

The OnZoomStart event fires before OnZoomEnd.

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