In the previous post I mentioned about manipulating SharePoint PeoplePicker control using JavaScript, in this post I will explain how to validate the InputFormTextBox contol using JavaScript. Here is the nice post by Becky Isserman on why not to use RequiredFieldValdator or InputFormRequiredFieldValidator with InputFormTextbox.

function ValidateComments()
{

    //retrieve the text from rich text editor.
    var text = RTE_GetRichEditTextOnly("<%= rteComments.ClientID %>");

    if (text != "")
    {
        return true;
    }

    else
    {
        alert('Please enter your comments.');

        //set focus back to the rich text editor.
        RTE_GiveEditorFocus("<%= rteComments.ClientID %>");
        return false;
    }

    return true;
}

<SharePoint:InputFormTextBox ID="rteComments" runat="server" RichText="true" RichTextMode="Compatible" Rows="10" TextMode="MultiLine" CausesValidation="true" ></SharePoint:InputFormTextBox>

<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" OnClientClick="return ValidateComments()" CausesValidation="true" />

- Jignesh