播放框架Twirl模板，比较javascript元素和scala变量 [英] Play framework Twirl template comparing javascript element and scala variable

问题描述

如下面的代码示例所示，我想比较scala helper元素内的javascript元素.但是，即使存在元素"abcde"，它也始终返回false.除了使用标记外，如何在scala帮助器元素中获取javascript值?

As shown in the code sample below I want to compare a javascript element inside a scala helper element. However it always returns false even when the element "abcde" is present. How can I get the javascript value inside the scala helper element other than using tags?

@(appSeq:Seq(String))
<script>
var app = 'abcde'
@if(appSeq.contains(<script>app</script>)) {
   alert('true');
} else {
   alert('false');
}
</script>

推荐答案

由于这个原因，这是不可能的:

It is not possible for this reason:

• var app = 'abcde'在JS VM中评估
• XML文字<script>app</script>)在Java VM中评估

• var app = 'abcde' is evaluated in the JS VM
• the XML literal <script>app</script>) is evaluated in the Java VM

因此，由于它们是两个不同的上下文，因此您无法共享从JS到Scala的变量.您可以做的是将变量从Scala传递到JS，因为首先评估Scala代码，所有值都将呈现在模板中.

So since they are two different contexts you can't share a variable from JS to Scala. What you can do is pass a variable from Scala to JS, since Scala code is evaluated first and all the values will be rendered in the template.

您需要在Scala XML中对'abcde'进行硬编码，或者更好地将其分配给Scala值，例如:

You need either to hard code 'abcde' in the Scala XML or better assign it to a Scala value like:

@(appSeq:Seq(String))
@app="abcde"
<script>
var app = "@app"
@if(appSeq.contains(<script>$app</script>)) {
   alert('true');
} else {
   alert('false');
}
</script>

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