How can i tell if javascript is enabled?

JavaScript is enabled in your web browser. Congratulations; you're one step closer to having a fun and fully featured online experience.

Remember that JavaScript is a "per browser" setting; if you have it enabled in Chrome, you might also have it disabled in Firefox on the same computer.

A lot of websites use Javascript as a part of their core functionality, and if you browse the internet without JavaScript enabled then you probably won't have the full experience that you normally would. Some websites may not work properly, others may not work at all.

What does JavaScript do?

JavaScript is a multipurpose programming language. There are many, many things that it can be used for. Generally speaking, it is used to allow Website developers to create web pages that have some intelligence built in to them. Instead of a webpage just being a plain page that has no interactivity, JavaScript can allow webpages adapt to what you do on the page, load new information, make decisions and respond to events.

For example, JavaScript might be used to validate a Mailing List Subscription form. So that when you try to submit a form the code runs and looks at each field on the form. If the code notices that you've forgotten to enter something in one of the fields (For example, your email address) it would pop up a warning and not let you submit the form until it is complete. Once that field is fixed then the form will be allowed to be submitted.

JavaScript can also be used to dynamically update part of a page without needing to reload the entire page. So for example, when you're using Facebook and you see a new notification come through; you can know that JavaScript was used to do that!

In fact, JavaScript was used to create the JavaScript detection on this page! If JavaScript is enabled then it updates the default "No" answer in to a "Yes" answer! (so that if JavaScript is not enabled, the default "No" remains as the answer). It's also used for Cookie detection, Flash version detection, Java version detection and so on.

Security considerations

As with most things, there is a flip side to JavaScript. There is an increasing number of ways for JavaScript to be used maliciously. JavaScript based attacks such as Cross Site Scripting and Click Jacking rely on JavaScript and can cause your security to be compromised. There are an increasing number of security minded people who do not just let JavaScript run on every single page they visit to decrease the chances of these attacks. There are browser extensions for Chrome and Firefox which can disable JavaScript by default but make it easy to turn it on only for trusted websites. The security minded web user would do well to check these extensions out.

We have a series of guides to help you enable JavaScript in your web browser.

Once you've got Javascript enabled, visit the Homepage to make sure your web browser is up to date and to get a full read-out of your web browser's capabilities.

More questions?

If you have any more questions about JavaScript and what it can do, use the contact form and we'll answer it and add your question here.

If you're a web developer, check the instructions on how to implement the

Instructions for web developers

You may want to consider linking to this site, to educate any script-disabled users on how to enable JavaScript in five most commonly used browsers. You are free to use the code below and modify it according to your needs.

On enable-javascript.com we optimize the script-disabled user experience as much as we can:

• The instructions for your browser are put at the top of the page
• All the images are inlined, full-size, for easy perusing
• This developer-centric message is out of the way.

We want your visitors to have JavaScript enabled just as much as you do!

I'd like to add my .02 here. It's not 100% bulletproof, but I think it's good enough.

The problem, for me, with the preferred example of putting up some sort of "this site doesn't work so well without Javascript" message is that you then need to make sure that your site works okay without Javascript. And once you've started down that road, then you start realizing that the site should be bulletproof with JS turned off, and that's a whole big chunk of additional work.

So, what you really want is a "redirection" to a page that says "turn on JS, silly". But, of course, you can't reliably do meta redirections. So, here's the suggestion:

...where all of the content in your site is wrapped with a div of class "pagecontainer". The CSS inside the noscript tag will then hide all of your page content, and instead display whatever "no JS" message you want to show. This is actually what Gmail appears to do...and if it's good enough for Google, it's good enough for my little site.

17

I assume you're trying to decide whether or not to deliver JavaScript-enhanced content. The best implementations degrade cleanly, so that the site will still operate without JavaScript. I also assume that you mean server-side detection, rather than using the

There is no good way to perform server-side JavaScript detection. As an alternative it is possible to set a cookie using JavaScript, and then test for that cookie using server-side scripting upon subsequent page views. However this would be unsuitable for deciding what content to deliver, as it would not distinguish visitors without the cookie from new visitors or from visitors who did not accept the JavaScript set cookie.

11

noscript blocks are executed when JavaScript is disabled, and are typically used to display alternative content to that you've generated in JavaScript, e.g.

Users without js will get the next_page link - you can add parameters here so that you know on the next page whether they've come via a JS/non-JS link, or attempt to set a cookie via JS, the absence of which implies JS is disabled. Both of these examples are fairly trivial and open to manipulation, but you get the idea.

If you want a purely statistical idea of how many of your users have javascript disabled, you could do something like:

then check your access logs to see how many times this image has been hit. A slightly crude solution, but it'll give you a good idea percentage-wise for your user base.

The above approach (image tracking) won't work well for text-only browsers or those that don't support js at all, so if your userbase swings primarily towards that area, this mightn't be the best approach.

6

This is what worked for me: it redirects a visitor if javascript is disabled

6

I'd suggest you go the other way around by writing unobtrusive JavaScript.

Make the features of your project work for users with JavaScript disabled, and when you're done, implement your JavaScript UI-enhancements.

https://en.wikipedia.org/wiki/Unobtrusive_JavaScript

10

If your use case is that you have a form (e.g., a login form) and your server-side script needs to know if the user has JavaScript enabled, you can do something like this:

This will change the value of js_enabled to 1 before submitting the form. If your server-side script gets a 0, no JS. If it gets a 1, JS!

0

Working Example:

    
    
    
    


    
Please enable JavaScript...
    
JavaScript dependent content here...

In this example, if JavaScript is enabled, then you see the site. If not, then you see the "Please enable JavaScript" message. The best way to test if JavaScript is enabled, is to simply try and use JavaScript! If it works, it's enabled, if not, then it's not...

2

Use a .no-js class on the body and create non javascript styles based on .no-js parent class. If javascript is disabled you will get all the non javascript styles, if there is JS support the .no-js class will be replaced giving you all the styles as usual.

 document.body.className = document.body.className.replace("no-js","js");

trick used in HTML5 boilerplate http://html5boilerplate.com/ through modernizr but you can use one line of javascript to replace the classes

noscript tags are okay but why have extra stuff in your html when it can be done with css

1

just a bit tough but (hairbo gave me the idea)

CSS:

.pagecontainer {
  display: none;
}

JS:

function load() {
  document.getElementById('noscriptmsg').style.display = "none";
  document.getElementById('load').style.display = "block";
  /* rest of js*/
}

HTML:

  

    Page loading....
  
  

    You don't have javascript enabled. Good luck with that.
  

would work in any case right? even if the noscript tag is unsupported (only some css required) any one knows a non css solution?

You can use a simple JS snippet to set the value of a hidden field. When posted back you know if JS was enabled or not.

Or you can try to open a popup window that you close rapidly (but that might be visible).

Also you have the NOSCRIPT tag that you can use to show text for browsers with JS disabled.

3

You'll want to take a look at the noscript tag.

0

Because I always want to give the browser something worthwhile to look at I often use this trick:

First, any portion of a page that needs JavaScript to run properly (including passive HTML elements that get modified through getElementById calls etc.) are designed to be usable as-is with the assumption that there ISN'T javaScript available. (designed as if it wasn't there)

Any elements that would require JavaScript, I place inside a tag something like:

Then at the beginning of my document, I use .onload or document.ready within a loop of getElementsByName('jsOnly') to set the .style.display = ""; turning the JS dependent elements back on. That way, non-JS browsers don't ever have to see the JS dependent portions of the site, and if they have it, it appears immediately when it's ready.

Once you are used to this method, it's fairly easy to hybridize your code to handle both situations, although I am only now experimenting with the noscript tag and expect it will have some additional advantages.

The noscript tag works well, but will require each additional page request to continue serving useless JS files, since essentially noscript is a client side check.

You could set a cookie with JS, but as someone else pointed out, this could fail. Ideally, you'd like to be able to detect JS client side, and without using cookies, set a session server side for that user that indicates is JS is enabled.

A possibility is to dynamically add a 1x1 image using JavaScript where the src attribute is actually a server side script. All this script does is saves to the current user session that JS is enabled ($_SESSION['js_enabled']). You can then output a 1x1 blank image back to the browser. The script won't run for users who have JS disabled, and hence the $_SESSION['js_enabled'] won't be set. Then for further pages served to this user, you can decide whether to include all of your external JS files, but you'll always want to include the check, since some of your users might be using the NoScript Firefox add-on or have JS disabled temporarily for some other reason.

You'll probably want to include this check somewhere close to the end of your page so that the additional HTTP request doesn't slow down the rendering of your page.

0

Add this to the HEAD tag of each page.

So you have:

With thanks to Jay.

A common solution is to the meta tag in conjunction with noscript to refresh the page and notify the server when JavaScript is disabled, like this:

In the above example when JavaScript is disabled the browser will redirect to the home page of the web site in 0 seconds. In addition it will also send the parameter javascript=false to the server.

A server side script such as node.js or PHP can then parse the parameter and come to know that JavaScript is disabled. It can then send a special non-JavaScript version of the web site to the client.

1

This is the "cleanest" solution id use:

If javascript is disabled your client-side code won't run anyway, so I assume you mean you want that info available server-side. In that case, noscript is less helpful. Instead, I'd have a hidden input and use javascript to fill in a value. After your next request or postback, if the value is there you know javascript is turned on.

Be careful of things like noscript, where the first request may show javascript disabled, but future requests turn it on.

You might, for instance, use something like document.location = 'java_page.html' to redirect the browser to a new, script-laden page. Failure to redirect implies that JavaScript is unavailable, in which case you can either resort to CGI ro utines or insert appropriate code between the tags. (NOTE: NOSCRIPT is only available in Netscape Navigator 3.0 and up.)

credit http://www.intranetjournal.com/faqs/jsfaq/how12.html

A technique I've used in the past is to use JavaScript to write a session cookie that simply acts as a flag to say that JavaScript is enabled. Then the server-side code looks for this cookie and if it's not found takes action as appropriate. Of course this technique does rely on cookies being enabled!

I think you could insert an image tag into a noscript tag and look at the stats how many times your site and how often this image has been loaded.

People have already posted examples that are good options for detection, but based on your requirement of "give warning that the site is not able to function properly without the browser having JS enabled". You basically add an element that appears somehow on the page, for example the 'pop-ups' on Stack Overflow when you earn a badge, with an appropriate message, then remove this with some Javascript that runs as soon as the page is loaded (and I mean the DOM, not the whole page).

code inside

enable java script and reload the page

website content.

now if JS is turned on you can just make the content inside your main_body visible as below

Why don't you just put a hijacked onClick() event handler that will fire only when JS is enabled, and use this to append a parameter (js=true) to the clicked/selected URL (you could also detect a drop down list and change the value- of add a hidden form field). So now when the server sees this parameter (js=true) it knows that JS is enabled and then do your fancy logic server-side.
The down side to this is that the first time a users comes to your site, bookmark, URL, search engine generated URL- you will need to detect that this is a new user so don't look for the NVP appended into the URL, and the server would have to wait for the next click to determine the user is JS enabled/disabled. Also, another downside is that the URL will end up on the browser URL and if this user then bookmarks this URL it will have the js=true NVP, even if the user does not have JS enabled, though on the next click the server would be wise to knowing whether the user still had JS enabled or not. Sigh.. this is fun...

To force users to enable JavaScripts, I set 'href' attribute of each link to the same document, which notifies user to enable JavaScripts or download Firefox (if they don't know how to enable JavaScripts). I stored actual link url to the 'name' attribute of links and defined a global onclick event that reads 'name' attribute and redirects the page there.

This works well for my user-base, though a bit fascist ;).

2

You don't detect whether the user has javascript disabled (server side or client). Instead, you assume that javascript is disabled and build your webpage with javascript disabled. This obviates the need for noscript, which you should avoid using anyway because it doesn't work quite right and is unnecessary.

For example, just build your site to say

Then, your script will simply do document.getElementById('nojs').style.display = 'none'; and go about its normal JS business.

1

Check for cookies using a pure server side solution i have introduced here then check for javascript by dropping a cookie using Jquery.Cookie and then check for cookie this way u check for both cookies and javascript

In some cases, doing it backwards could be sufficient. Add a class using javascript:

// Jquery
$('body').addClass('js-enabled');

/* CSS */
.menu-mobile {display:none;}
body.js-enabled .menu-mobile {display:block;}

This could create maintenance issues on anything complex, but it's a simple fix for some things. Rather than trying to detect when it's not loaded, just style according to when it is loaded.

I would like to add my solution to get reliable statistics on how many real users visit my site with javascript disabled over the total users. The check is done one time only per session with these benefits:

• Users visiting 100 pages or just 1 are counted 1 each. This allows to focus on single users, not pages.
• Does not break page flow, structure or semantic in anyway
• Could logs user agent. This allow to exclude bots from statistics, such as google bot and bing bot which usually have JS disabled! Could also log IP, time etc...
• Just one check per session (minimal overload)

My code uses PHP, mysql and jquery with ajax but could be adapted to other languanges:

Create a table in your DB like this one:

CREATE TABLE IF NOT EXISTS `log_JS` (
  `logJS_id` int(11) NOT NULL AUTO_INCREMENT,
  `data_ins` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `session_id` varchar(50) NOT NULL,
  `JS_ON` tinyint(1) NOT NULL DEFAULT '0',
  `agent` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`logJS_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8;

Add this to every page after using session_start() or equivalent (jquery required):

Create the page JSOK.php like this:

I've figured out another approach using css and javascript itself.
This is just to start tinkering with classes and ids.

The CSS snippet:
1. Create a css ID rule, and name it #jsDis.
2. Use the "content" property to generate a text after the BODY element. (You can style this as you wish).
3 Create a 2nd css ID rule and name it #jsEn, and stylize it. (for the sake of simplicity, I gave to my #jsEn rule a different background color.

The JavaScript snippet:
1. Create a function.
2. Grab the BODY ID with getElementById and assign it to a variable.
3. Using the JS function 'setAttribute', change the value of the ID attribute of the BODY element.


The HTML part.
1. Name the BODY element attribute with the ID of #jsDis.
2. Add the onLoad event with the function name. (jsOn()).

Because of the BODY tag has been given the ID of #jsDis:
- If Javascript is enable, it will change by himself the attribute of the BODY tag.
- If Javascript is disable, it will show the css 'content:' rule text.

You can play around with a #wrapper container, or with any DIV that use JS.

Hope this helps to get the idea.

Detect it in what? JavaScript? That would be impossible. If you just want it for logging purposes, you could use some sort of tracking scheme, where each page has JavaScript that will make a request for a special resource (probably a very small gif or similar). That way you can just take the difference between unique page requests and requests for your tracking file.