A simple directive to add "matches" validation, e.g. to check if a password matches a confirmation

angular-simple-matches-validator.js

function crMatches () {
	return {
		require: 'ngModel',
		scope: {
			crMatches: '='
		},
		link: function(scope, elem, attrs, ctrl) {
			scope.$watch('crMatches', function (newValue) {
				if (newValue) { ctrl.$setValidity('matches', newValue === elem.val()); }
			});
			ctrl.$validators.matches = function (modelValue) { return scope.crMatches === modelValue; }
		}
	};
}