Disabling and enabling a html input button

Using Javascript

• Disabling a html button

  document.getElementById("Button").disabled = true;
  

• Enabling a html button

  document.getElementById("Button").disabled = false;
  

• Demo Here

Using jQuery

All versions of jQuery prior to 1.6

• Disabling a html button

  $('#Button').attr('disabled','disabled');
  

• Enabling a html button

  $('#Button').removeAttr('disabled');
  

• Demo Here

All versions of jQuery after 1.6

• Disabling a html button

  $('#Button').prop('disabled', true);
  

• Enabling a html button

  $('#Button').prop('disabled', false);
  

• Demo Here

P.S. Updated the code based on jquery 1.6.1 changes. As a suggestion, always use the latest jquery files and the prop() method.