Angular是否会在相同的$ digest循环中重新评估相同的$ watch表达式？

Question

If I have a template in the form of:

<div ng-controller="testCtrl">
    <div ng-if="exFn()"></div>
    <div ng-if="exFn()"></div>
</div>

will the ngController scope call exFn twice per $digest, or will the scope remember that the exFn() expression's new value and use it instead of reevaluating the expression?

Answer 1

It will call exFn four times. Twice to find out the original value for each watch, then twice again to see if they are stable. This makes sense: the function could depend on external state.