Binaryworld - IsClientScriptEnabled - Checking if the client script support is reque ... [ ASP.net -> Server Controls

If you develop a custom control and want to give the option to output client-side javascript code, you'll likely have a EnableClientScript that allows the developer to specify whether the js code will be generated or not. However, before generating and outputting the js, you should also check whether it is supported by the target client browser. The following function takes in input a Boolean value (that will be the value of your EnableClientScript property), and returns the same value only if javascript code is supported, otherwise it returns False.

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' Return True if client script support is requested and possible
Function IsClientScriptEnabled(Byval value as Boolean) As Boolean
  ' we need a Try block because accessing the Browser
  ' property at design time may throw
  Try
    ' Return False if DOM version is too low.
    If Page.Request.Browser.W3CDomVersion.Major < 1 Then
      Return False
    End If

    ' Return False if EcmaScript version is too low.
    If Page.Request.Browser.EcmaScriptVersion.CompareTo(New Version(1, _
      2)) < 0 Then
      Return False
    End If

    ' if all tests passed, return the input value
    IsClientScriptEnabled = value
  Catch
    ' return False if any error occurs
    Return False
  End Try
End Function

Within the method where you generate the control's output code (for example from the overridden Render method), instead of doing something like this:

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If EnableClientScript Then
' generate and output javascript code
End If

You'll do:

Click here to copy the following block

If IsClientScriptEnabled(EnableClientScript) Then
' generate and output javascript code
End If