title: disable backspace to prevent default value of input to be erased JQUERY
body: <p>I have a registration form and there has an input for cellphone number, i set a default value "+63" on it when it is clicked. Now i want to disable backspace when it detected +63 value of input</p>
  
  <pre><code>$('#contact').click(function(){
      var code = "+63";
      $('#contact').val(code);
  });    
  
  $('#contact').on('change keydown', function(e){
          //codes here
  
  });
  </code></pre>