append time in js file

Do you have a server-side scripting language available, like PHP or ASP.net?

Replace you line with the following :

<script>
var modificationtime =  new Date().getTime();
var script = document.createElement("script");
script.async = false;
script.charset = "utf8",
script.src = "./test.js?version=" + modificationtime;
var head = document.head || document.getElementsByTagName("head")[0] || document.documentElement;
head.insertBefore( script, head.firstChild );
</script>

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var modificationtime =  new Date().getTime();

this code will verytime return current date and time,what i need is the date and time should only change when file is modified.
i need file modification date and time....

without server, it's not possible until you set this value somewhere and download it with ajax...

that what i need a common configurable program or entry in tomcat?
any sample code or link would be helpful

Let me try this one again:  Do you have a server-side scripting language available, like PHP or ASP.net?

It's servlet at server side

<script src"./test.js?version=modificationtime">

Are these lines all in JSP files ?

yes

How many web pages do you have in your web app?
 Could you rewrite each URL in the src attribute for each script tag?  I am suggesting something like
 <script src"./test.js?version=<m:modTime file="test.js" />">
where I have substituted  modificationtime with a custom tag.  The custom tag could get the last modified time for the file. It is easy to create a custom file using "tag files". I could post some demonstration code tomorrow. Just tell us about your file structure.
Is test.js in the same folder as your JSP?
Would  
<script src"test.js?version=modificationtime">  
work just as well? Notice the change in the URL.

Here is how to do this on the client side using jQuery ajax

Live Demo

function getLast(fileName) {
    $.ajax({
        type: "HEAD",
        async: true,
        url: fileName,
        success: function(message,text,response){
           var lm = response.getResponseHeader('Last-modified');
           if (lm) {
             $("#res").text(lm +"("+new Date(lm).getTime()+")");
           }
        }

    });
}

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Here are a couple more ideas.
Does your Tomcat use Java 1.7 or 1.8 ? If so, there is WatchService  
http://docs.oracle.com/javase/7/docs/api/java/nio/file/WatchService.html   
 that might come in handy.
 Could you rewrite each URL in the src attribute for each script tag?  I am suggesting something like
 <script src"./test.js?version=${applicationScope.testmodificationtime}">
 You could use the  WatchService to keep the application-scoped variables up to date. The variables could be set in a ServletContextListener.

Alternatively, if WatchService is too complicated, then use A TimerTask to periodically check for file changes. It could keep the  application- scoped variables up to date.

You could use the  WatchService to keep the application-scoped variables up to date.

Any sample code of above would be helpful