How to prevent a tagbox from accepting duplicate values?

[kingor2001]

How to prevent a tagbox from accepting duplicate value?
I can input some duplicate values in a tagbox now, but sometimes I want the tagbox prevent from adding a new value which existing in tagbox's values.

[jarry]

Define a validation rule and apply it to the tagbox.

Code:

$.extend($.fn.validatebox.defaults.rules, {
	duplicatetag: {
		validator: function(value,param){
			value = $.trim(value).replace(/\,$/,'');
			var vv = value.split(',');
			if((new Set(vv)).size != vv.length){
				return false;
			}
			return true;
		},
		message: 'Duplicate tags.'
	}
})