在视图中使用RegEx

问题描述

我有一个像这样的控制器:

I have a controller like this:

function Ctrl( $scope ){

    $scope.str = " Misty Mountain Hop ";

}

和这样的视图:

<div ng-controller="Ctrl">

    <p>{{ str }}</p>       <!-- This one is ok -->
    <p>{{ str.split( "Mountain")[0] }}</p>   <!--Even this one is fine too -->
    <p>{{ str.replace( /Mountain/ , "Plain" ) }}</p>  <!-- This one is bad -->

</div>

因此，如果我尝试使用 replace 方法，则会出现错误:

So if i try to use a replace method , it gives an error:

Syntax Error: Token 'Mountain' is unexpected ...

http://jsfiddle.net/H3ztj/

问题是:为什么?

推荐答案

由于您的问题是为什么?"，因此答案是插值块中的表达式不是JavaScript表达式，而是角度表达式.它们看起来很像JavaScript(故意)，但是Angular使用自己的解析器来解析代码.

Since your question was "Why?", the answer is that expressions in interpolation blocks are not JavaScript expressions, but Angular expressions. They look a lot like JavaScript (on purpose), but Angular uses its own parser to parse the code.

这样，它不仅可以对表达式进行一次评估:它还可以执行诸如分析依赖项之类的工作，因此它可以监视成分并在这些成分发生更改时进行更新.它还可以计算相对于 $ scope 的表达式，以便 {{foo}} 返回 $ scope.foo 而不是全局变量.称为 foo (依次使ngRepeat之类的东西起作用).

That way it can do more than just evaluate the expression once: it can also do things like analyze the dependencies, so it can watch the ingredients and update when those ingredients change. It can also evaluate the expression relative to the $scope, so that {{foo}} returns $scope.foo rather than a global variable called foo (which in turn makes things like ngRepeat work).

当Angular团队实现Angular表达式时，他们显然没有实现正则表达式.这不足为奇-无论如何，这种代码都应该在您的控制器中，您可以在其中进行测试.

When the Angular team implemented Angular expressions, they obviously didn't implement regular expressions. That's not surprising -- that kind of code should be in your controller anyway, where you can test it.

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