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Spellchecking Multiple Text Areas


How to spell-check multiple text-areas at once using a custom text source.


To spell check multiple text sources:

  • Define a Custom Text Source that accepts a single "sources" parameter. The parameter will accept an array of element text that will be passed to it.

  • In the get_text() method for the custom text source, get the text from each control and join these strings with separators to make a single string.

  • In the set_text() method parse the "text" property and use the parts to populate the "sources" array.

  • Create an array of HtmlElementTextSource that in turn takes the contents of each textbox in the constructor.

  • Create an instance of your new custom text source object, passing the array of HtmlElementTextSource in the constructor.

  • Call the RadSpell client object set_textSource() method, passing the new custom text source object instance.


HtmlElementTextSource is defined in the Telerik.Web.UI.Spell assembly, and registered for availability to JavaScript within RadSpell.js. RadSpell.js is normally a resource and not visible to you, but you can find the JavaScript source in the Telerik UI for ASP.NET AJAX installation directory under "\scripts".

This general approach can be used not just for TextBoxes, but for spell checking any combination of controls on a web page.


At runtime the joined string might look like:
"bad spelling 1<controlSeparator><br/></controlSeparator>bad spelling 2<controlSeparator><br/></controlSeparator>bad spelling 3"
But is displayed as in Figure 1 .
The "<controlSeparator>" tags are arbitrary and can be any unique string that is used to join in the get_text() method and parse back apart in the set_text() method. The "<br> tags are necessary to show each misspelling on a separate line in the "Not in Dictionary' section of the dialog.

Figure 1: Errors shown from multiple text areas without the </controlSeparator> keyword

<telerik:RadCodeBlock ID="RadCodeBlock1" runat="server">
   <script type="text/javascript">
       function MultipleTextSource(sources)
         this.sources = sources;
         this.get_text = function()
            var texts = [];
            for (var i = 0; i < this.sources.length; i++)
               texts[texts.length] = this.sources[i].get_text();
            return texts.join("<controlSeparator><br/></controlSeparator>");
         this.set_text = function(text)
            var texts = text.split("<controlSeparator><br/></controlSeparator>");
            for (var i = 0; i < this.sources.length; i++)
       function spellCheck()
           var sources =
               new Telerik.Web.UI.Spell.HtmlElementTextSource($get('TextBox1')),
               new Telerik.Web.UI.Spell.HtmlElementTextSource($get('TextBox2')),
               new Telerik.Web.UI.Spell.HtmlElementTextSource($get('TextBox3'))
           var spell = $find('<%= RadSpell1.ClientID %>');
           spell.set_textSource(new MultipleTextSource(sources));
<asp:ScriptManager ID="Scriptmanager1" runat="server">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<telerik:RadSpell RenderMode="Lightweight" ID="RadSpell1" runat="server" ButtonType="None" />
<input id="Button1" type="button" value="Spell Check All" onclick="spellCheck();" />