Question

I am developing a site using Asp.net MVC 3 with Razor.

In the _Layout.cshtml (the master page) I want to put a logic based on whether or not the browser enables javascript.

What is the simplest way to make this logic?

For the sake of simplicity, let the master page just output as follows:

@if(....)//need to modify
{ <p>javascript enabled...</p>}
else {<p>javascript disabled...</p>}

Answer 1

There’s no way to find this out on the server, therefore there’s no way to find out before the first page is loaded. The best you can do is to put a bit of Javascript into the page that sets a cookie or posts an AJAX response to the server telling it that Javascript is active, so you can do something about it on subsequent page requests. Even apart from the obvious problem of the first page load, it’s a bad strategy since the user may switch off Javascript in the meantime while your server still thinks it’s active.

Graceful degradation/progressive enhancement are the keywords here. Make your page assume by default that no Javascript is active and act accordingly, i.e. serve plain HTML in either case. Include Javascript that will “upgrade” the site’s functionality if Javascript is active. Let the client figure out if Javascript is working or not and give it the means to work in either case.