是否可以从jsp的java部分执行javascript函数？

Question

In jsp , I want a function defined in javascript

<script type="text/javascript">
function forSignup(){

    if(document.getElementById("sign").style.display=='none')
    {

        document.getElementById("sign").style.display='block';
        document.getElementById("login form").style.display='none';
    }

    else
    {
        document.getElementById("login form").style.display='block';
        document.getElementById("sign").style.display='none';
    }
</script> 

to be executed when called from the java part of jsp <% %> on a condition when a servlet sends a value of an integer as 1 .

Is it possible to do ?

if yes please tell me how should I perform it ?

Answer 1

I assume this is roughly what you're looking for. If a server side variable (intValue) is equal to 1, then call the function, otherwise do not.

<% if (intValue == 1) { %>
    <script type="text/javascript">
        forSignup();
    </script>
<% } %>

Bear in mind though, that you're not actually calling this Javascript function "from Java". You are merely ensuring that the Javascript function is called based on the server side condition, dependent on the integer value in question.

Answer 2

您可以使用<c:if>块基于 JSP 中的变量包含 JavaScript。

Answer 3

JavaScript can be executed from Java code, but it isn't simple, and the code you posted has to run from the DOM and thus can't be handled server-side. Moreover, using scriptlets is strongly discouraged; it's much better to prepare the model for a page (usually using a framework such as Spring MVC) and then use templates for rendering only.

What you're wanting to do is conditional logic, determining whether elements are displayed based on some state such as whether the user is logged in. Use <c:if> to selectively include code in the rendered HTML (and just set CSS directly instead of taking a detour through JavaScript).

Answer 4

if you want to execute java code in javascript method

<script >
 function login(){
 <% System.out.println("Hiiiiiiiii"); 

 %>
 var password="test"
 }
</script>