Find if JavaScript is enabled/disabled in JSP

Question

I have a web page where a part of the page is loaded via AJAX, but I also wanted to make it work if JavaScript is not enabled.

so, i wrote the code as

<script>
    fetchCitiesAndDisplay ();
</script>
<noscript>
    <%
        out.print(Cities.getHtml ());
    %>
</noscript>

where

fetchCitiesAndDisplay ()

is a javaScript Method, which will get the content (executes the code in Cities.java) and displays it.

Cities.java

is a Java class which will collect the cities from database and generates the html content to be displayed.

When JavaScript is off, everything works great.. as the ajax call will not be executed and only Cities.getHtml () will be called once.

but, when JavaScript is enabled, The Ajax call is also executed and Cities.getHtml () is also called.. even-though the display looks right because of tag, Cities.java will get the call twice for the same data, and it eats up a lot of time...

How to solve this?

Answer 1

i have to agree with @jfriend00, its not possible to identify if javascript is enabled using 1 page

You can use javascript to set a hidden variable with some value, when the page submits you can check for it and identify if javascript is enabled or not.. but this requires 1 request/response cycle, may be you can have an interim page which forwards the request to the intended page (with the hidden variable i discussed above).

Answer 2

Why not have your javascript code load a a tiny html/image/etc snippet on page load. If javascript is enabled, you can see that file was requested. If it's disabled, there will be no request for that file.

Answer 3

I'm wondering if maybe you don't understand how <noscript> works. It doesn't come into play in your server-side template so whatever server-side logic you put in there will ALWAYS execute whether javascript is ultimately enabled or not in the browser.

Therefore, this doesn't make a whole lot of sense to me because the HTML inside <noscript> is always going to be generated whether javascript is on or off. It will always be in the page. So, if it's always in the page, then why fetch it via ajax when javascript is on?