javascript - Angular 表达式 {{::}} 中的两个冒号是什么意思？

Question

有什么区别:

{{::office.name}}

和

{{office.name}}

在 angularJS 中？

Answer 1

One-time binding ^{From Angular Docs.}

An expression that starts with :: is considered a one-time expression. One-time expressions will stop recalculating once they are stable, which happens after the first digest if the expression result is a non-undefined value (see value stabilization algorithm below).

在许多情况下，值只需要显示在 View 中，永远不会从 View 或 Controller 中更新。但是，如果使用双向绑定(bind)，$digest 将检查每个循环中表达式的任何变化，这是没有必要的。在这些情况下，应该在表达式之前使用 ::。如上述声明所述，对于这种情况，这比双向绑定(bind)语法更有效。

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博客:AngularJS one-time binding syntax来自 @Todd Motto

In a nut shell, when we declare a value such as {{ ::foo }} inside the DOM, once this value becomes defined, Angular will render it, unbind it from the watchers and thus reduce the volume of bindings inside the $digest loop. Simple!