AngularJS Example:

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<div ng-app>
  
  <div ng-controller="TodoCtrl">
      <textarea ng-model="myStr"></textarea>
  </div>
    
</div>

CSS

textarea {
    
height: 100px;
}

JavaScript

function TodoCtrl($scope) {
  $scope.myStr = 'aaaa\nbbbb\nccccc';
      $scope.$watch('myStr', function(myStr){
          $scope.myArray = myStr.split('\n');
          console.log('$scope.myArray', $scope.myArray);
      });
      

}