角偷懒一次为前pressions结合 [英] Angular lazy one-time binding for expressions

问题描述

AngularJS从此版本1.3.0-beta.10一个新的功能：懒一次性绑定。

简单的前pressions可与 pfixed $ P $ :: ，告诉角度停止前pression看后首次评估。给出的常见的例子是这样的：

 ＆LT; D​​IV＆GT; {{:: user.name}}＆LT; / DIV＆GT;
 

有没有类似的语法为前pressions像下面的人？

 ＆LT; D​​IV NG-IF =user.isSomething＆放大器;＆安培; user.isSomethingElse＆GT;＆LT; / DIV＆GT;
＆LT; D​​IV纳克级={classNameFoo：user.isSomething}＆GT;＆LT; / DIV＆GT;
 

解决方案

是的。您可以preFIX每前pressions与：，甚至鸡舍 ngIf 或 ngClass ：

 ＆LT; D​​IV NG-IF =：:( user.isSomething＆放大器;＆安培; user.isSomethingElse）＆GT;＆LT; / DIV＆GT;
＆LT; D​​IV纳克级={:: classNameFoo：user.isSomething}＆GT;＆LT; / DIV＆GT;
 

其实，<一个href=\"https://github.com/angular/angular.js/blob/cee429f0aaebf32ef1c9aedd8447a48f163dd0a4/src/ng/parse.js#L1027\">the code 简单地检查，在恩pression前两个字符是：以激活一次性绑定（然后删除它们，从而括号甚至没有必要）。其他一切不变。

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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