Example to remove all script block in HTML

This is example how to remove script block in HTML.
This method will be very useful if you want to validate the html passed from input string do not have any script block.

Example HTML have script block :

<div> this is the information </div>
<script>alert('Your computer have security vulnerable');</script>

Example ASPX Code :

Note : This html using Editor Controller in AjaxToolkit library

 <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">  
 </asp:Content>  
 <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">  
   <ajaxToolkit:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">  
   </ajaxToolkit:ToolkitScriptManager>  
   Input Text :  
   <cc1:Editor ID="Editor1" runat="server" />  
   <br />  
   <asp:Button ID="Button1" runat="server" Text="Save" onclick="Button1_Click" />  
   <br />  
   <asp:Literal ID="Literal1" runat="server"></asp:Literal>  
 </asp:Content>  

Code Behind :

   protected void Page_Load(object sender, EventArgs e)  
     {  
     }  
     protected void Button1_Click(object sender, EventArgs e)  
     {  
       string inputHTML = Editor1.Content;  
       Literal1.Text = RemoveScripts(inputHTML);  
     }  
     /// <summary>  
     /// Regular expression match for the scripts.  
     /// </summary>  
     private Regex _RegExRemoveScripts;  
     /// <summary>  
     /// Regular expression match for the scripts.  
     /// </summary>  
     private Regex RegExRemoveScripts  
     {  
       get  
       {  
         // Expression groups: none   
         return _RegExRemoveScripts ?? (_RegExRemoveScripts = GetRegex(@"<script[ >](?:[^<]|<(?!/script))*</script>",  
           RegexOptions.Compiled | RegexOptions.IgnoreCase));  
       }  
     }  
     /// <summary>  
     /// Gets the regular expression specified by a matching pattern, optionally specifying processing options.  
     /// </summary>  
     /// <param name="pattern">Pattern to match</param>  
     /// <param name="options">Processing options</param>  
     private Regex GetRegex(string pattern, RegexOptions options)  
     {  
       return CreateRegex(pattern, options);  
     }  
     /// <summary>  
     /// Creates a new regular expression  
     /// </summary>  
     /// <param name="pattern">Pattern to match</param>  
     /// <param name="options">Processing options</param>  
     private Regex CreateRegex(string pattern, RegexOptions options)  
     {  
       return new Regex(pattern, EnsureCorrectOptions(options));  
     }  
     /// <summary>  
     /// Adds CultureInvariant option when there is ignore case to ensure correct behavior in Turkish culture.  
     /// </summary>  
     /// <param name="options">Options to be modified</param>  
     private RegexOptions EnsureCorrectOptions(RegexOptions options)  
     {  
       if (options.HasFlag(RegexOptions.IgnoreCase) && !options.HasFlag(RegexOptions.CultureInvariant))  
       {  
         // Add CultureInvariant option when there is ignore case to ensure correct behavior in Turkish culture  
         options |= RegexOptions.CultureInvariant;  
       }  
       return options;  
     }  
     /// <summary>  
     /// Removes the scripts from the given HTML text.  
     /// </summary>  
     /// <param name="htmlText">HTML text to process</param>  
     public string RemoveScripts(string htmlText)  
     {  
       // Remove all script blocks  
       htmlText = RegExRemoveScripts.Replace(htmlText, "");  
       return htmlText;  
     }  

How to use ?

1. Copy paste the above code in your code behind
2. Try call method RemoveScript(string htmlCode)

Output :

Before Filter :

After Filter :

Hopefully this example can help someone.

By Mohd Zulkamal
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