In your hooks/<tablename>-dv.js file
(replace the <tablename> with your actual tablename)
// Set input to reject space. File hooks/tablename-dv.js
$j('#<fieldname>').keyup(function () {
$j(this).val($j(this).val().replace(/s/g, ''));
});(don’t forget to replace the <fieldname> with the corresponding fieldname)