在Java函数中使用javascript变量 [英] using javascript variable inside the java function

问题描述

需要一个有关如何在java作用域内访问javascript变量的解决方案. 在以下代码中，<％= toppings [k]％> k是一个JavaScript变量，我如何访问它，我收到一条消息，因为 JVM不知道k

wanted a solution on how to access the javascript variable inside the java scope. In the below code, <%=toppings[k]%> k is a javascript variable how can i access that, I am getting a message as k is not known to JVM

function value_transitAccountCounter(i){
    alert('welcome -->'+i);
    for(var k=0;k<5;k++){
        if(i==k){
            return '<%=toppings[k]%>';
        }
    }
}

推荐答案

您的Java代码在服务器上运行 .您的JavaScript代码正在客户端上运行 .因此，您不能在服务器上使用k，在页面完成，发送到浏览器并执行其中的JavaScript之前，它不存在.

Your Java code is running on the server. Your JavaScript code is running on the client. So you can't use k on the server, it doesn't exist until the page is finished, sent to the browser, and the JavaScript therein executed.

从您的代码看来，您只需要访问存储在服务器端toppings数组中的字符串.您有两种选择:

From your code, it looks like you just need to access the strings stored in the server-side toppings array. You have two choices:

1. 将整个toppings数组作为JavaScript数组输出到页面的脚本.然后，您可以在客户端使用它.

1. Output the entire toppings array to the page's script as a JavaScript array. Then you can just use it client-side.

让您的value_transitAccountCounter函数进行 ajax调用您的服务器端代码，询问toppings[i]的值是什么.您需要更改value_transitAccountCounter以接受用于返回值而不是实际返回值的回调，因为ajax调用将是异步的(value_transitAccountCounter将在ajax调用完成之前返回，因此，在获得值). (进行同步ajax调用是可能，但这是一个非常非常糟糕的主意，您最好假装这是不可能的.它完全锁定了大多数浏览器的UI，而调用时执行，令人难以置信使用户烦恼.)

Have your value_transitAccountCounter function make an ajax call to your server-side code, asking what the value of toppings[i] is. You'll need to change value_transitAccountCounter to accept a callback to use to return the value rather than actually returning it, because the ajax call will be asynchronous (value_transitAccountCounter will return before the ajax call completes and thus, before you have the value to return). (It's possible to make synchronous ajax calls, but it's a very, very bad idea and you're better off pretending it isn't possible. It completely locks up the UI of most browsers while the call is executing, incredibly irritating for users.)

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