title: How to detect input field change in angularjs
body: <p>I have group of input fields( I am not using form),I need to detect if any one of them is changed by user, before user leave the page, I need to show a popup, How can I make it happen? I need a function like checkchanges, if changes, will return false/true. something like this.
  I try to use$scope.$watch and angular.forEach to loop all input ng-model, but seems like doesn't work out.</p>