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>
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>
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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