Added new kb article htmlchart-disable-legend-item-click (#620)

Co-authored-by: KB Bot <kb-bot@telerik.com>

knowledge-base/htmlchart-disable-legend-item-click.md

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+---
+title: Disable  Leged Item Click
+description: This article demonstrates how to disable the click functionality on the legend items in RadHtmlChart for ASP.NET AJAX, preventing the default show/hide behavior of corresponding chart segments.
+type: how-to
+page_title: Disable  Leged Item Click 
+slug: htmlchart-disable-legend-item-click
+tags: radhtmlchart, asp.net ajax, legend, unclickable, prevent default
+res_type: kb
+ticketid: 1668631
+---
+
+## Environment
+
+<table>
+<tbody>
+<tr>
+<td>Product</td>
+<td>RadHtmlChart for ASP.NET AJAX</td>
+</tr>
+<tr>
+<td>Version</td>
+<td>All</td>
+</tr>
+</tbody>
+</table>
+
+## Description
+
+I want to disable the ability to click on chart legend items, preventing the default behavior of showing or hiding the corresponding chart segments.
+
+This KB article also answers the following questions:
+
+- How to make legend items in RadHtmlChart non-interactive?
+- How to prevent the default toggle behavior on legend item click in RadHtmlChart?
+- How to stop chart segments from hiding when clicking on their legend items?
+
+## Solution
+
+To make legend items unclickable and prevent the default behavior of showing or hiding the corresponding chart segments in RadHtmlChart, attach the `legendItemClick` event and prevent its default action. 
+
+The following example demonstrates how to achieve this by using a Pie Chart as an illustration. However, this approach is applicable to any chart type that supports legend items in RadHtmlChart.
+
+1. Attach the `OnLegendItemClick` client event to the RadHtmlChart.
+
+2. Implement the `onLegendItemClick` function to prevent the default behavior.
+
+Here is how you can configure the RadHtmlChart:
+
+````ASP.NET
+<telerik:RadHtmlChart runat="server" ID="RadChart1" Width="500px">
+    <PlotArea>
+        <Series>
+            <telerik:PieSeries>
+                <SeriesItems>
+                    <telerik:PieSeriesItem Y="20" Name="name 1" />
+                    <telerik:PieSeriesItem Y="30" Name="name 2" />
+                    <telerik:PieSeriesItem Y="50" Name="name 3" />
+                    <telerik:PieSeriesItem Y="40" Name="name 4" />
+                </SeriesItems>
+            </telerik:PieSeries>
+        </Series>
+    </PlotArea>
+    <ClientEvents OnLegendItemClick="onLegendItemClick"/>
+</telerik:RadHtmlChart>
+````
+
+Include the following JavaScript function in your page:
+
+````JavaScript
+function onLegendItemClick(e) {
+    e.preventDefault();
+}
+````
+
+By preventing the default action in the `onLegendItemClick` function, clicking on legend items will no longer toggle the visibility of the corresponding chart segments, making the legend items effectively unclickable in terms of interactive behavior.
+
+## See Also
+
+- [RadHtmlChart Documentation](https://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/overview)
+- [Client-Side Programming Overview](https://docs.telerik.com/devtools/aspnet-ajax/controls/htmlchart/client-side-programming/overview)