Dynamics CRM Portals - Disable checkbox using Custom JavaScript on Portal Entity Form onLoad. Login to CRM & Navigate to Entity Form. Go to the Custom Javascript Area and past the below script to disable the checkbox field on the CRM. $(document).ready( function () { var IsChecked= $( "#attributelogicalname" ).is( ":checked" ); if (IsChecked){ $( " #attributelogicalname " ).show(); $( " #attributelogicalname _label" ).show(); $( " #attributelogicalname " ).attr( "disabled" , true ); } else { $( " #attributelogicalname " ).hide(); $( " #attributelogicalname _label" ).hide(); } }); Happy CRMing..!!