Ng-keyup callback not called when created in JS

Adding a function callback of ng-keyup and ng-keydown using setAttribute from Javascript doesn’t work - any ideas?
I have this in my controller:
$scope.$on('$ionicView.enter', function(e) { var input = document.createElement("textarea"); input.setAttribute("ng-keyup","updateTextArea($event)"); input.setAttribute("ng-keydown","updateTextArea($event)"); input.placeholder = "Things"; var parent = document.getElementsByClassName('target')[0]; parent.appendChild(input); });

<ion-view view-title={{}}> <ion-content> <div class="target"></div> </ion-content> </ion-view>

If I was to change the HTML to include the textarea, it works as expected (Resizing the textarea height)