Assign JavaScript variable to Java Variable in JSP

Question

Ello there   I m trying to assign the value of a javascript variable to a java variable  But I don t have clue how to do this  Say for example I have this    lt html gt   lt head gt      lt script type  text javascript  gt         function return variable              var a    hello             return a               lt  script gt   lt  head gt   lt body gt    lt        The java code    String b     how do I get that javascript variable here    gt    lt  body gt   lt  html gt

User · Answer

you cant do it   because jsp is compiled and converted into html server side whereas javascript is executed on client side  you may set the value to a hidden html element and send to servlet in request just in case you want to use for further

User · Answer

Java script plays on browser where java code is server side thing so you can t simply do this   What you can do is submit the calculated variable from javascript to server by form-submission  or using URL parameter or using AJAX calls and then you can make it available on server  HTML   lt input type  hidden  id  hiddenField   gt    make sure this fields lays under  lt form gt    Javascript  document getElementById  hiddenField   value yourCalculatedVariable    on server you would get this as a part of request

User · Answer

As JavaScript is client side and JSP is Server side   So Javascript does not execute until it gets to the browser  But Java executes on the server  So  Java does not know the value of the JavaScript variable   However you assign value of Java variable to JavaScript variable

User · Answer

JavaScript is fired on client side and JSP is on server-side  So I can say that it is impossible

User · Answer

The answer is You can t  Java  in your case JSP  is a server-side scripting language  which means that it is compiled and executed before all javascript code  You can assign javascript variables to JSP variables but not the other way around  If possible  you can have the variable appear in a QueryString or pass it via a form  through a hidden field   post it and extract the variable through JSP that way  But this would require resubmitting the page   Hope this helps

User · Answer

I think there s no way to do that  unless you pass the value of the JavaScript var on the URL  but it s a ugly workaround

User · Answer

You need to read something about a JSP s lifecycle  Try this  http   en wikipedia org wiki File JSPLife png  JavaScript runs on the client  but in order to change the jsp  you need access to the server  This can be done through Ajax http   en wikipedia org wiki Ajax  28programming 29    Here are some Ajax-related links  http   www openjs com articles ajax xmlhttp using post php  http   www w3schools com ajax tryit asp filename tryajax first

[java] Assign JavaScript variable to Java Variable in JSP

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