Disable the postback on an <ASP:LinkButton>

ASPX code:

<asp:LinkButton ID="someID" runat="server" Text="clicky"></asp:LinkButton>

Code behind:

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        someID.Attributes.Add("onClick", "return false;");
    }
}

What renders as HTML is:

<a onclick="return false;" id="someID" href="javascript:__doPostBack('someID','')">clicky</a>

In this case, what happens is the onclick functionality becomes your validator. If it is false, the "href" link is not executed; however, if it is true the href will get executed. This eliminates your post back.

This may sound like an unhelpful answer ... But why are you using a LinkButton for something purely client-side? Use a standard HTML anchor tag and set its onclick action to your Javascript.

If you need the server to generate the text of that link, then use an asp:Label as the content between the anchor's start and end tags.

If you need to dynamically change the script behavior based on server-side code, consider asp:Literal as a technique.

But unless you're doing server-side activity from the Click event of the LinkButton, there just doesn't seem to be much point to using it here.

You can do it too

...LinkButton ID="BtnForgotPassword" runat="server" OnClientClick="ChangeText('1');return false"...

And it stop the link button postback