Is it a bad idea to set directive scope to false, considering the limitations on broadcasting in an isolated scope?

There is a unique situation I am trying to tackle where I need to use $broadcast within a directive's linking function that has an isolated scope. Unfortunately, broadcasting from inside an isolated scope becomes challenging as the directive scope does not inherit from the parent scope, as explained in this source.

I am aware that setting scope: false on my directive would cause it to use the parent's scope, which could lead to naming collisions and reduce reusability due to crowding of the parent scope.

Considering this, I wonder if using scope: false on a directive meant for reuse might have further drawbacks beyond organizational concerns. Is it just about preference and cleanliness or are there more negative implications?

As far as I know, there seems to be no other method than broadcasting inside a directive's linking function to achieve the desired functionality, apart from perhaps modifying a service (which isn't feasible given the parent scope hierarchy). Therefore, using $broadcast appears to be the only available option at the moment. Any insights would be greatly appreciated.

Thank you!

EDIT: Just to clarify, I aim to broadcast from the isolated scope downwards to the children of the parent scope:

JS

.controller('parent', function ($scope) {
  $scope.parent = 'parentProperty';
})
.directive('isolate', function() {
  return {
    scope: {},
    template: '<div ng-click="click()">Click</div>',
    link: function (scope) {
      scope.click = function () {
        console.log('clicked,but no broadcast');
      scope.$broadcast('event', 'string');
      }
    }
    };
})
.directive('child', function () {
  return {
  link: function(scope) {
    scope.$on('event', function (e, event) {
      console.log(event);
    });
  }
};
});

HTML

<body ng-controller="parent">
    <div isolate>Click me to broadcast
      </div>
      <div child>
        </div>
  </body>

PLNKR: http://plnkr.co/edit/wKDOP4UpdgDFrHvzY0UN?p=preview

Answer №1

It seems there may have been a misunderstanding of the content in the article you linked to. The ability to broadcast events to isolate scopes is indeed possible, as indicated in the post you referenced:

While it's true that the isolate scope can listen for events propagated through the scope hierarchy, it cannot access scope values from its parent scope, such as "pingCount."

The key concept to remember in AngularJS is that the $broadcast method sends events downwards in the parent/child scope structure (including isolate scopes). For sending events upwards, you would utilize $emit.

If your intention is to use $emit within your directive's link function, this will allow the event to travel up towards the parent scopes. You can find more information on this in the AngularJS documentation here.

UPDATE

A straightforward approach involves utilizing two events. Initially, the directive uses $emit() to dispatch an event to the parent scope. Subsequently, the parent scope employs $on() to await this event. Once triggered, it proceeds to employ $broadcast() to disseminate another event to all child scopes.

For a practical example, refer to this Plunkr demo.

This method is basic and may encounter limitations. Consider exploring alternative options like leveraging the require property of directives alongside a controller equipped with an API that allows seamless communication between child directives.

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