jQuery Validate unique email addresses
jQuery Validate offers a lot of great features out of the box, but one feature it's lacking is validating if something is not found is a list. Fortunately, it's super easy to add your own validators. In my case I want to find if something doesn't exist in a list.
jQuery.validator.addMethod('uniqueEmail', function(value) { var currentEmails = 'an array from somewhere with emails lower cased'; //NOTE: this check is case sensitive, so make sure you lower case both values being compared return $.inArray(value.toLowerCase(), currentEmails) === -1; }, 'Email has already been added.')
$('#ccEmail').validate({ errorElement: 'div', rules: { CCEmail_Address: { email: true, uniqueEmail: true //use the custom validator } } });