RadMultiColumnComboBox for ASP.NET AJAX is based on the Kendo UI MultiColumnComboBox Widget. Thus, it exposes the Client-side API and methods offered by the widget and mainly provides a wrapper and API for working with the MultiColumnComboBox on the server.
        You can get Client-side Object Reference to the MultiColumnComboBox control in order to use its API like this: 
        
        
var radMultiColumnComboBoxObject = $find("<%=RadMultiColumnComboBox1.ClientID %>");
        
    
    
        The most commonly used RadMultiColumnComboBox client-side methods are:
    
    
        - 
            set_enabled—Enables or disables the widget.
        
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            set_readOnly—Toggles the readonly state of the widget. When the widget is readonly it doesn't allow user input.
        
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            open—Opens the popup.
        
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            close—Closes the widget popup.
        
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            toggle—Opens or closes the widget popup.
        
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            search—Searches the data source for the provided value and displays any matches as suggestions.
        
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            get_value and set_value—Gets or sets the value of the MultiColumnComboBox.
        
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            get_text and set_text—Gets or sets the text of the MultiColumnComboBox. Widget will select the item with same text. If there are no matches then the text will be considered as a custom value of the widget.
        
You can find the full client-side API of the control in the RadMultiColumnComboBox Client-side API documentation article.
    
    
        Get Client-side Object Reference to the Kendo MultiColumnComboBox widget in order to use its API
    
    
        There are two ways to get a reference to the Kendo MultiColumnComboBox widget in order to use its API:
        
            - 
                Use the get_kendoWidget method the RadMultiColumnComboBox client-side object exposes. You can get the RadMultiColumnComboBox object through the $find() MS AJAX method:
                
 
 varradMultiColumnComboBoxObject  = $find("<%=RadMultiColumnComboBox1.ClientID %>"); //the standard script control object
 varkendoMultiColumnComboBoxObject = radMultiColumnComboBoxObject.get_kendoWidget(); //the Kendo widget
 
 
- Use the standard Kendo approach for getting the widget through the data-attributes of the DOM element:
                
 
 varkendoMultiColumnComboBoxObject = $telerik.$("#<%=RadMultiColumnComboBox1.ClientID %>").data("kendoMultiColumnComboBox"); //the jQuery selector must get the RadMultiColumnComboBox1 span element