title: Django Form, check validate before submit. (HTML)
body: <p>For a regular html form, I could use java script to validate input onsubmit, which means the submit button is work only for a valid input, hence no http response required. 
  However, I am unable to do the same thing for a django form. 
  A Django form in html is simply as {{form}}.
  for example {{form.title}} is the form for title.
  So I am looking for a way to validate the Django form at front end (in HTML). only the valid input would be post</p>