contenteditable tag will not work directly with angular’s ng-model because the way contenteditable rerender the dom element on every change.

You have to wrap it with a custom directive for that:

JS:

angular.module('customControl', ['ngSanitize']).
directive('contenteditable', ['$sce', function($sce) {
  return {
    restrict: 'A', // only activate on element attribute
    require: '?ngModel', // get a hold of NgModelController
    link: function(scope, element, attrs, ngModel) {
      if (!ngModel) return; // do nothing if no ng-model

      // Specify how UI should be updated
      ngModel.$render = function() {
        element.html($sce.getTrustedHtml(ngModel.$viewValue || ''));
      };

      // Listen for change events to enable binding
      element.on('blur keyup change', function() {
        scope.$evalAsync(read);
      });
      read(); // initialize

      // Write data to the model
      function read() {
        var html = element.html();
        // When we clear the content editable the browser leaves a <br> behind
        // If strip-br attribute is provided then we strip this out
        if ( attrs.stripBr && html == '<br>' ) {
          html="";
        }
        ngModel.$setViewValue(html);
      }
    }
  };
}]);

HTML

<form name="myForm">
 <div contenteditable
      name="myWidget" ng-model="userContent"
      strip-br="true"
      required>Change me!</div>
  <span ng-show="myForm.myWidget.$error.required">Required!</span>
 <hr>
 <textarea ng-model="userContent"></textarea>
</form>

Source it from the original docs