JavaScript is Good, But Should Not be Relied Upon

There was a time, years ago, when the only reason to use JavaScript on a website was to produce cliché effects; flashing, scrolling, fading and popups to name but a few. It was slow, clunky and not a very nice language to write code in. Browsers required different code to do the same thing as another browser, the whole thing was a mess. People would overuse sites like dynamic drive to achieve all sorts of pointless effects, falling snow, page transition effects, and who can forget, the disabling of right mouse clicking by making a popup appear, which was about as effective as putting up a sign which says "Please don't push this button".

Recently however, JavaScript has lost it's status as as annoyance and has become common place on lots of main stream websites. It's picked up a certain bit of elegance and if used correctly, can add a lot to the experience of a site. Browsers can now parse JavaScript at speeds which make it viable to use for visual effects, and it can be used to trigger events and to change parts of the page dynamically without having to refresh the entire page (AJAX for example).

With libraries like jQuery and Prototype it has become even easier, as they add a new layer between the browser and the programmer, meaning you don't need to know about all the little inconsistencies between the browser implementations of JavaScript. The library will hide these from you, so you can concentrate on writing the code and let the library deal with getting it to behave the same in every browser.

A combination of browser support, libraries, speed and ease of use means JavaScript is now much more attractive than it was 5 or 10 years ago. It no longer has the stigma associated with 1990s sites and has become a much more civilised solution to web development. All the big sites use it, Google has auto-completion when you type, Digg uses it to show extra comments, etc.

There's no doubt that JavaScript is incredibly useful and a great way to make the interactive experience of a website seamless. But you should never rely on JavaScript for a part of your website to function.

Everyone Uses JavaScript

Everyone has JavaScript enabled right? Well I'm afraid not. If you've made any part of your website only accessible to those with JavaScript enabled, then you've cut out 6% of the people who use the internet (June 2009 figures from thecounter). That's a lot of people, no matter how you look at it. Yes, you can just put a disclaimer on the site saying "This only works with JavaScript". But that isn't going to make it any less annoying for those 6% of users.

You may be asking yourself, "Why would anyone have JavaScript disabled in this day and age?". Well, for any number of reasons. Companies sometimes disable JavaScript for security reasons, people may disable it because it makes their browser experience faster if they leave it off, people could be using a text browser, or a mobile phone browser that doesn't support JavaScript.

If a visitor comes to your site and doesn't have JavaScript enabled, yet your site heavily relies on JavaScript to function, then they'll leave immediately. Yet it is so simple to make things work without JavaScript.

Progressive Enhancement vs Graceful Degredation

There are two main programming philosophies when dealing with a new technology. Progressive Enhancement and Graceful Degredation. The latter means that you build the site using the new technology first. Make sure it works in all the latest browsers and that all of your fancy code runs well. Then you go back and add bits to make sure that if someone views it in an older browser, it will still work fine. Progressive Enhancement is the other way around. You make the main functionality of the site work without the new technology, then add it in afterwards so that it works for everyone.

Think of it like this. If you're building a skyscraper, how would you do it? You have two options.

  1. Build the foundations, making sure it's a solid base. Then add each floor one by one.
  2. Build all of the floors right to the top, then go back and make sure the base is strong enough for people to walk around on the bottom floor.

It would seem number 1 is the best choice, but for me, it depends on the scenario. For CSS I generally use Graceful Degredation, not from any pre-thought out plan, it's just how I happen to do it. When I write a new style, I will be developing on just one browser (generally Firefox/Linux), once I am happy with the style, I will validate it with the W3C validator service. I will have generally made a few typos here and there. Once the CSS is valid, I'll check it out in other browsers, usually the latest versions of Opera, Chrome, IE and Firefox. It will generally look the same in all of those, with just perhaps a few minor tweaks here and there. Then I will try it out in the older versions, IE7, Firefox 2, etc. Based on how many inconsistencies there are, I may just use a quick and nasty CSS hack to target just those browsers, or give a new CSS file entirely (in the case of IE6/7). This is graceful degredation at work. I know it works in the later stuff, now I'm making it work in the older stuff without breaking it in the newer stuff.

The problem with this method, is that sometimes you'll edit something to work in an older browser, but then find you've broken it in the newer browsers, so you start going back and forth with yourself trying to get it to work in both.

Progressive Enhancement is the other way around. You first make it work without any "extra stuff", then you add on the extra bits afterwards, for those who have the technology to view the extra bits. It means current people can still use the site, but those who are ahead in technology make use of the latest stuff. This is my preferred method, because it means you won't leave anything out, and will slowly build your site up from a base. It also means you generally aren't going to break something you've already coded, which saves time in the long run.

This is how you should add JavaScript to a site. First make the site work without JavaScript at all. Disable it in your browser and make the site function. Then go ahead and add all of the JavaScript goodness you want, safe in the knowledge that those 6% of people will still be able to use the site. Yeah, so it won't have lovely fade effects, or quick AJAX, but it will still work.

Progressive Enhancement also has an added bonus. It's actually generally a quicker and easier method than Graceful Degredation. It should be a no brainer!

You're a Hypocrite!

I recently (well, end of last year) made the decision that I will no longer build website for IE6. It is my strong opinion that IE6 is holding back web development. It takes nearly double the amount of time to make a site work in IE6 as well as all the other browsers out there. To quote a bit from Falling Down, this isn't economically viable! Yes OK, a lot of people still use IE6 (around 9%), but it won't go away unless we make a stand.

Unfortunately, it isn't going to go anywhere soon, because it was around for so long without any sort of competition, which means lots and lots of companies used it to build internal tools and sites, which now will only work in IE6. They would need to spend lots of money to upgrade their internal things to work in more modern browsers, so they will simply stick with what they have. Why spend money, when it works as it is. There is also the fact that "Internet Explorer" was very cleverly named to have the word "Internet" in it. You'll find the majority of non technical people will not understand what a browser is, and simply think that "Internet Explorer" is in fact "The Internet".

You could say I'm being quite hypocritical. Here I am trying to argue that we should make the time to make our sites work for 6% of people who don't have JavaScript enabled, yet I'm advocating cutting off the 9% of IE6 users out there for exactly the same reasons.

Well, it's not that simple. There are some fundamental differences,

  1. To make a site work without JavaScript takes very little effort. Compared to the effort required to make a site work in IE6, which normally takes double the time as you have to build two sites. One to work in IE6, and one to work in everything else.
  2. There is no excuse for someone to be using IE6 exclusively. It's heavily outdated, and I'm betting most people's kettle's are actually newer than IE6. JavaScript on the other hand has legitimate reasons to be turned off. Security, speed, text browser, mobile browser, accessibility.
  3. Making your site work in IE6 only benefits people who use IE6. Making your site work without JavaScript has several other advantages. If you accidentally introduce a JavaScript bug or the JavaScript fails to load correctly, your site is resilient and won't be crippled, as it will still work without JavaScript. Search Engines generally can't follow JavaScript links, so making them work without JavaScript means search engines will be able to index your site better, etc
  4. As new browsers come out, they may introduce inconsistencies in the way JavaScript works. Being able to fallback to a non-JavaScript solution means you don't have to immediately spend time and effort getting it to work in new browsers. Once you've made the site work in IE6 and put the effort in, that's it, it's never going to be useful for anything else.

Maybe you still think I'm a hypocrite, and that's fine. Let me know your thoughts in the comments. I'm curious to know where people stand on this subject.

Stop Waffling and Get to The Good Stuff

OK, so now to get to the code. Let's imagine you have a shopping website that relies entirely on JavaScript. Your links might look something like this,
<a href="javascript:addToBasket()">Buy Item</a>

That's great, it works for you and adds the item to your shopping cart. Now turn JavaScript off, and you're not going anywhere. There's a link on the page which doesn't work. A user is furiously clicking it, but it won't add anything to their cart. They go to another site instead, and you just lost a sale. Good luck if anyone using a text based browser wants to buy anything, as it won't work for them either.

(This has actually happened to me in the past, not because I've had JavaScript disabled, but because the code had a typo in it and wasn't loading correctly, so I couldn't purchase the item and went somewhere else instead).

If you build a website, you should make it work for as many people as you possibly can. (Yes, even IE6 if you have the time and the money). Imagine buying a car, only to find you can only use it on 94% of the roads. Great, until you hit one of those 6% of roads.

Here's a better way to make the link. This follows the Graceful Degredation process I talked about earlier. We had our original link, which works in JavaScript, and now we're editing it to work without JavaScript too.
<a href="buyitem.php?item=awesomestuff" onlick="addToBasket()">Buy Item</a>

(We'll ignore for the moment it's a bad idea to use a GET parameter for something like this, that's a PHP issue and not in the scope of this post. I'll write about it sometime in the future).

If you make the "addToBasket" function return false at the end, then if JavaScript is enabled, the link will not be followed and only the JavaScript will execute. But if JavaScript is turned off, then the link is followed, and the user can still add things to their basket, (with a script you've written, but for this example, I'm assuming the JavaScript would have called the same PHP script with AJAX anyway, it just will now redirect back to the same page). Everyone is happy and everyone can buy things.

But there's a better way.

The Better Way

Now there's another issue. If I don't have JavaScript enabled, I'm still downloading the "onclick='addToBasket()'" but of the code. It's not much, but over a whole page it could be a lot. It also makes the markup look untidy. Not a big issue, but I'm OCD about that sort of stuff. Also as we saw earlier, there's a better way to do things. Lay the foundations of your skyscraper first.

If you've never heard the term "unobtrusive JavaScript" before, I suggest you do a quick Google search to see what it's all about. Basically it's called unobtrusive because the markup stays the same and has no JavaScript calls in it at all. It is pure HTML, as it was meant to be. HTML for markup, CSS for presentation and JavaScript for behaviour. So rather than littering your HTML with "onclick=''", etc. It is nice and clean.

Since JavaScript only needs to work when JavaScript is enabled, you can use the JavaScript itself to modify the DOM once the page has loaded, in order to add the "onclick" event handlers for you. But this also means there's no chance of someone clicking a JavaScript link before the page has fully loaded, which can sometimes cause problems, since the JavaScript version of the link won't be active until the page has fully loaded. jQuery makes this sort of stuff extremely easy.

On page load, you modify your links to add the JavaScript handlers. If a person has JavaScript disabled, they don't even need to waste the bandwidth of downloading the JavaScript, and the HTML will be nice and clean making the page load faster for them. But if they do have JavaScript enabled, the site will be modified to work as a JavaScript version.

Suppose we now create the link like this,
<a href="buyitem.php?item=awesomestuff" id="buyitem-awesomestuff" class="buyitem">Buy This</a>

This is nice and clean, has an ID to unique identify it, has a CSS class so we can style it appropriately, and is free of JavaScript. This will work for everyone. Now we can add a JavaScript file to the page and "AJAXify" this link without ever needing to touch the HTML again. So an example using jQuery would be something like this,
            var url = "buyitem.php?item=" + $(this).attr("id").substring(8);
                  function(val) { alert("Item added to cart"); },
            return false;  // So we don't follow the normal link.  

When the page loads, this will go over all links with the "buyitem" class, pick out the item string from the id, and add an "onclick" event handler to submit the AJAX request. We haven't touched the HTML at all, but by just adding JavaScript we've made it work with AJAX for those with JavaScript, and we're safe in the knowledge it will still work for those without.

Note : The example is just to demonstrate unobtrusive JavaScript. You will want to have a much better callback than the one above. The callback should check that the item was actually added, rather than just show an alert either way as the example above does. You probably want to parse the id to get everything after the "-" character, rather than just substring(8), since the id may change in future, etc.

Final Thoughts

Every so often I come across forums, or answers on the internet, which give JavaScript solutions to common problems (which is perfectly fine), but then they say something like "This will only work with JS enabled, but everyone has it on nowadays, so screw those who don't, they probably won't want to look at your site anyway". This is just completely the wrong attitude. With a little bit of extra work you can make it work both ways and have a site that works for 100% of users, not just 94%. People argue that because it's 2009, everyone should have JavaScript enabled. While perhaps they should it doesn't necessarily mean that they have to. There are legitimate reasons to have it disabled, and those people shouldn't be excluded.

Another common issue people tend to solve with JavaScript is input validation. If your input validation is just a JavaScript file then you have failed as a web developer. All I need to do to bypass your checks is to disable JavaScript. It's the equivalent of using JavaScript for login/password (something I have actually seen on a production site before). By all means use JavaScript for input validation, it means the user can see something is wrong without having to submit the form, a great interface response. But don't rely on it. Always always always make sure you also have server-side validation for the same things, otherwise you're just asking for a world of trouble. It may feel like you're just repeating code, but it's worth it in the long run.

So I guess my point is this. Never rely on JavaScript to do a job. Form validation, prevent dual submits, links, etc. Always make sure they also work without JavaScript, otherwise you've either opened your site up for abuse, or made it unusable to 6% of the people who use the internet. Either way it's not very good.
Picture of Rich Adams.

Hi! I'm Rich. By day I work on cloud security at Indeed. By night I wear a cape and fight crime1. I'm on Twitter as @r_adams, and also used to write things on the PagerDuty blog.

1 probably not true


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