javascript disable enable button based on form change code example

Example 1: How disable button jquery

$( "button" ).prop( "disabled", true );

Example 2: jquery enable submit button

//jQuery 1.6+ use:
$("#submitButtonID").prop('disabled', true); //disable 
$("#submitButtonID").prop('disabled', false); //enable

//jQuery 1.5 and below use:
$("#submitButtonID").attr('disabled','disabled'); //disable 
$("#submitButtonID").removeAttr('disabled'); //enable