title: Validate a text field while typing input into a text box
body: <p>I am trying to implement a sign-up form that asks users to input the desired login-id.
  The user inputs the desired login-id into a text box. </p>
  
  <p>I would like to perform validation on this text box to see if the desired login-id is available without having to submit the form.</p>
  
  <p>The validation should start happening say after the 5th character is input into the text box.</p>