javascript - AngularJS: ng-if not working in combination with ng-click?

Question

Given this test case using AngularJS 1.2 rc3: http://plnkr.co/edit/MX6otx (repeated below)

1.

<li ng-init="toggle1 = false">
    ng-if toggle1: {{ toggle1 }}
    <p>
        <button ng-if="!toggle1" ng-click="toggle1 = true">Turn On</button>
        <button ng-if="toggle1" ng-click="toggle1 = false">Turn Off</button>
        does not work
</li>

2.

<li ng-init="obj={toggle2:false}">
    ng-if obj.toggle2: {{ obj.toggle2 }}
    <p>
        <button ng-if="!obj.toggle2" ng-click="obj.toggle2 = true">Turn On</button>
        <button ng-if="obj.toggle2" ng-click="obj.toggle2 = false">Turn Off</button>
        then why does this work?
</li>

Questions:

1. Why does 1 not work?
2. Should 1 work?
3. Why does 2 work?
4. Should 2 work?
5. Can I rely 2 to work in future updates of AngularJS?

Answer 1

1. Why does 1 not work?: Because an ngIf defines its own scope, which prototypically inherits from its parent scope (just like ngRepeat). So, when you change the value of a field inside an ngIf, you change it in the ngIf scope, and not in its parent scope.
2. Should 1 work?: No
3. Why does 2 work?: Because in that case you modify the content of an object which is referenced by the ngId scope, through inheritance.
4. Should 2 work?: Yes
5. Can I rely 2 to work in future updates of AngularJS?: Why shouldn't you?

This scope inheritance mechanism is explained very well in https://github.com/angular/angular.js/wiki/Understanding-Scopes