表达式的 Angular 惰性一次性绑定 [英] Angular lazy one-time binding for expressions

问题描述

AngularJS 从 1.3.0-beta.10 版本开始有一个新特性:惰性一次性绑定"".

简单的表达式可以以 :: 为前缀，告诉 angular 在表达式第一次计算后停止观察.给出的常见示例类似于:

{{::user.name}}

是否有类似以下表达式的语法?

<div ng-if="user.isSomething && user.isSomethingElse"></div><div ng-class="{classNameFoo: user.isSomething}"></div>

解决方案

是的.你可以用 :: 前缀每个表达式，即使是 ngIf 或 ngClass:

<div ng-if="::(user.isSomething && user.isSomethingElse)"></div><div ng-class="::{classNameFoo: user.isSomething}"></div>

实际上，代码只需检查表达式中的前两个字符是否为 : 以激活一次性绑定(然后删除它们，因此甚至不需要括号).其他一切都保持不变.

AngularJS has a new feature since the version 1.3.0-beta.10: the "lazy one-time binding".

Simple expressions can be prefixed with ::, telling angular to stop watching after the expression was first evaluated. The common example given is something like:

<div>{{::user.name}}</div>

Is there a similar syntax for expressions like the following ones?

<div ng-if="user.isSomething && user.isSomethingElse"></div>
<div ng-class="{classNameFoo: user.isSomething}"></div>

解决方案

Yes. You can prefix every expressions with ::, even the ones in ngIf or ngClass:

<div ng-if="::(user.isSomething && user.isSomethingElse)"></div>
<div ng-class="::{classNameFoo: user.isSomething}"></div>

Actually, the code simply checks that the two first characters in the expression are : in order to activate the one-time binding (and then removes them, thus the parenthesis aren't even needed). Everything else remains the same.

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