title: How disable RequiredFieldValidator in script
body: <p>I have TextBox with RequiredFieldValidator on my page.
  I also have link that calls some simple javascript.</p>
  
  <pre><code>&lt;asp:TextBox ID="TextBox1" runat="server" /&gt;
  &lt;asp:RequiredFieldValidator
  ID="RequiredFieldValidator4" runat="server" ControlToValidate="TextBox1"
  Display="Dynamic" /&gt; 
  &lt;asp:LinkButton   ID="Link1" runat="server" OnClientClick="DoSomething(); return false;" CausesValidation="false"Text="Do" /&gt;
  
  function DoSomething() {
  textbox1.val("blah"); }
  </code></pre>
  
  <p>When user type something into textbox and then delete that text and focus next control - then validator fires.
  Then user can use link that adds text using javascript. TextBox1 text is no longer empty but RequiredFieldValidator still shows error message. How to prevent that?</p>