AngularJS中ngModel指令的范围是什么？

Question

I think that ngModel directive should not create new scope as it needs to make changes in the variables of parent scope.
Please correct me if i am wrong .
And also looking at the source of ngModel directive scope is not defined so it should not create a new scope for directive.

var ngModelDirective = ['$rootScope', function($rootScope) {
  return {
    restrict: 'A',
    require: ['ngModel', '^?form', '^?ngModelOptions'],
    controller: NgModelController,
    // Prelink needs to run before any input directive
    // so that we can set the NgModelOptions in NgModelController
    // before anyone else uses it.
    priority: 1,
    compile: function ngModelCompile(element) {
      // Setup initial state of the control
      element.addClass(PRISTINE_CLASS).addClass(UNTOUCHED_CLASS).addClass(VALID_CLASS);

      return {
        pre: function ngModelPreLink(scope, element, attr, ctrls) {
          var modelCtrl = ctrls[0],
              formCtrl = ctrls[1] || modelCtrl.$$parentForm;

          modelCtrl.$$setOptions(ctrls[2] && ctrls[2].$options);

          // notify others, especially parent forms
          formCtrl.$addControl(modelCtrl);

          attr.$observe('name', function(newValue) {
            if (modelCtrl.$name !== newValue) {
              modelCtrl.$$parentForm.$$renameControl(modelCtrl, newValue);
            }
          });

          scope.$on('$destroy', function() {
            modelCtrl.$$parentForm.$removeControl(modelCtrl);
          });
        },
        post: function ngModelPostLink(scope, element, attr, ctrls) {
          var modelCtrl = ctrls[0];
          if (modelCtrl.$options && modelCtrl.$options.updateOn) {
            element.on(modelCtrl.$options.updateOn, function(ev) {
              modelCtrl.$$debounceViewValueCommit(ev && ev.type);
            });
          }

          element.on('blur', function() {
            if (modelCtrl.$touched) return;

            if ($rootScope.$$phase) {
              scope.$evalAsync(modelCtrl.$setTouched);
            } else {
              scope.$apply(modelCtrl.$setTouched);
            }
          });
        }
      };
    }
  };
}];

Also I don't understand why ngModel directive requires ngModel itself.
require: ['ngModel', '^?form', '^?ngModelOptions'] Can't it be ignored and written like
require: ['^?form', '^?ngModelOptions']
If not then please explain why ?

Answer 1

ngModel doesn't create an isolated scope. The reason ngModel is listed in the require array is so that its controller (NgModelController) will be injected into the link function. Notice the ctrls argument that is passed into the ngModelPostLink function. Because ngModel is listed in the array, ctrls[0] will be an instance of the NgModelController. ctrls[1] is the form controller, etc.