jQuery: enabling/disabling datepicker

Question

In my php-file, I want to use the jQuery Datepicker.

When my file loads, I create the Datepicker disabled.

Then, when a special field in my php-file (it is a

Answer 1

   $("#datepicker").datepicker({
     dateFormat:'dd/M/yy',
     minDate: 'now',
     changeMonth:true,
     changeYear:true,
     showOn: "focus",
    // buttonImage: "YourImage",
     buttonImageOnly: true, 
     yearRange: "-100:+0",  
  }); 

  $( "#datepicker" ).datepicker( "option", "disabled", true ); //missing ID selector