Month: April 2009

Many developers and designers nowadays may not be aware of how important a responsive and better user experience can determine a good and a poor website. Having good coding practice and efficient use of built in methods are important but there are more than just these. This is a practical check list for an optimized website that should be practice during your web development for faster and better user experiences. Please take note that some of the point listed here may contradict the practice of a good SEO friendly site.

1. Compressed JavaScript and CSS

I will say this is the basic thing that most web developer will be well aware of. The benefit to do this is so that your user will not have to wait the extra few second for your page to be loaded due to the extra kb that were not optimal on your JavaScript and CSS files. This actually makes a difference when your users are running a slow connection.

2. Use Cache-Control header

Since web pages are getting more and more richer which means more images, script, flash, content and etc.,  caching your site is the best way to experience faster respond time for your users. A first time user may have to make more HTTP request, but subsequent page visits will definitely reduce the number of HTTP request making your site feel faster. There are three way of caching,

1.      Via <meta> tags (<meta http-equiv="Expires"...>)

2.      Programmatically by setting HTTP headers (CGI scripts etc.)

3.      Through web server configuration files (httpd.conf)

And for good practice, static page should implement a 'Never expire' policy since its static, there won't be much changes on it. Additional, dynamic components will use Cache-Control header to help browser with conditional requests.

3. Check for orphaned files and missing images

Missing files are problematic because they result in error messages. In a way, it is great to have error message displayed because it's informative but in terms of speed optimization for web pages, they have a larger disadvantage. The reason is when the browser is looking for any missing item in your site; it is consuming resources which slower down page processing. So check all those links on your site and you won't need to have any error message to began with.

4. Use a content-distribution network

A content delivery network (CDN) is a great way to improve download times for your static images or heavy loaded files as CNS is a collection of web servers distributed across multiple locations to deliver content more efficiently to users. The server selected for delivering content to a specific user is based on the approximation of the network load. For example, the server with the fewest network hops or the server with the quickest response time is chosen.

The other advantage of CDNs is that they are separate domain. So what if it is a separate domain? Well, you might not know that your browser do limit the number of concurrent connection to a single domain whenever a page loads which delay other stuff on your page from loading concurrently. But your browser is capable of opening up a new thread to other domain and by using CDNs, you get the benefit of concurrent download of your site material. P.S you may want to host your JavaScript framework library with Google.

5. Content First

This is a practice for web development that you should consider having. Always load the content first follow by other assets of your web site. The reason is those users are not really interested in all your banners and footer stuff that you are going to show to them. They are there for your content. Therefore, display those first! This can be done by placing your content block (the div of the content) right after the body tag. This way, it will display the content first follow by other necessary things in your site. This also promotes better SEO crawling.

6. StyleSheet top, Script bottom

Top means on the header while bottom means right before the closing body tag. For better user experience, showing them display will most likely gain a better respond. Script will be at the bottom because they are most likely not as important as content and navigation bar. Unless your site cannot live without JavaScript which you shouldn't than it can be on the top. (The reason why JavaScript should not be so dependent is because of security issue of XSS where most users will use tools such as NoScript from Firefox to protect themselves against hackers)

7. External JavaScript and CSS

If you are still wondering whether Inline is better or external file is better than go with external file. The core benefit is external files will be cached by the browser and lesser HTTP request needed in subsequence page visit. On the other hand, Inline on the page will just make life difficult for the developers to maintain and required more HTTP request since main HTML files are always being requested.

8.  Avoid Redirect

Redirect slow down user experience. This is simple to explain why, imagine yourself being redirect by the page. The page that you just went in rendered nothing which means you has to wait for the actual HTML file to arrive.  After the page has arrived, it is being rendered again. How much time has this process wasted?

9. Use trailing slash.

This is something important you should be aware of. With and without slash at the back of the URL does make a differences in term of speed. Unless it is an extension type if you do not include a trailing slash at the back it will slow the process. For example,

We will not have to add trailer for the below example

Hungred.com/useful-Information/index.php

Hungred.com/useful-Information/

But if this does not have a trailing slash,

Hungred.com/useful-Information

What happen behind the scenes is that a 404 Error has been generated and a redirect is performed which causes a large amount of resources wasted. Most developers are not aware of such problem when dealing with URLs.

10. Make favicon.ico Small and Cacheable

The favicon.ico is an image that stays in the root of your server. It's a necessary evil because even if you don't care about it the browser will still request it, so it's better not to respond with a 404 Not Found. Also since it's on the same server, cookies are sent every time it's requested. This image also interferes with the download sequence, for example in IE when you request extra components in the onload, the favicon will be downloaded before these extra components.

So to mitigate the drawbacks of having a favicon.ico make sure:

• It's small, preferably under 1K.
• Set Expires header with what you feel comfortable (since you cannot rename it if you decide to change it). You can probably safely set the Expires header a few months in the future. You can check the last modified date of your current favicon.ico to make an informed decision.

11. Gzip Compression

Compression reduces response times by reducing the size of the HTTP response which there is a better article that explain Gzip and how to setup it on http://betterexplained.com/articles/how-to-optimize-your-site-with-gzip-compression/

12. Remove Duplicate Scripts

Everyone should know duplicate script means doing extra stuff which is bad.  It will cause multiple HTTP request and slow your web response.  If your site did not have caching ability, this means double the work for HTTP request as each subsequence page means repeating request

13.  Flush Browser Buffer Early

This means that you should send your partially ready HTML response to your browser so that it can start fetching components while the backend is busy with the rest of the HTML page. In PHP, there is a function flush() which can be use and placed after the close html tag and opening body tag. This helps to display your page concurrently making your user feel the responsiveness from your site.

14. Use GET for AJAX Requests

Unless you are sending data to be stored on the server, it is best to use GET method.  POST required 2 steps that is to send the header first (details for server) then the data. On the other hand, GET only required one TCP packet to be send but have a maximum length of 2k in IE so it's a 2K limit for all browser since your application should be cross browser compatibility. So GET is meant for retrieving information while POST is meant for sending data easy right?

15. Preload Components

Preload takes advance of the browser when it is in idle state. Since it is not doing anything, might as well preload some images to store in cache for the following pages. Usually you would want to have this function to speed up your overall site to allow your user to experience better responsiveness when moving towards other subsequence pages.

16. Reduce the Number of DOM Elements

A complex page means more bytes to download and it also means slower DOM access in JavaScript. And if you are using jQuery, this is definitely something you should be aware of. It makes a difference if you loop through 300 or 3000 DOM elements on the page. A simple test can be done on Firebug's console by writing the following code

document.getElementsByTagName('*').length

17. Minimize the Number of iframes

It is costly to run a iframes in a browser even if it render a blank page. The costly here means that if the page is loading two sites at one time, its like there are another site that is fighting with your site for resources to be rendered out to the page.

18. Reduce Cookie Size

Cookie is exchanged in the HTTP headers between web server and browser. Thus, it is important to keep the size small as larger cookie takes longer to download. It is best to remove unnecessary cookies and be mindful of setting the appropriate domain level so that sub-domain is not affected.

19. Minimize DOM Access

Accessing DOM elements with JavaScript is slow so in order to have a more responsive page, you should:

• Cache references to accessed elements
• Update nodes "offline" and then add them to the tree
• Avoid fixing layout with JavaScript

20. Don't use images to represent text

Image takes longer to load and you won't want your user to guess where is the navigation bar when the image takes too long to load. Always use text as it is faster and less heavy than image. Furthermore, it is good for SEO as search engine spider recognize text instead of image.

21. Choose <link> over @import

Since we want better responsiveness for our user from our website, we placed our CSS tag on the top of the page. But if you use @import instead of <link>, IE will behave as if the <link> is placed at the bottom of the page so it is best not to use @import.

22. Develop Smart Event Handlers

Instead of attaching many event handlers to each element, we use event delegation and event bubble which only attach a single handler to the parent. Let's say you have many buttons inside a div, attach only one event handler to the div wrapper, instead of one handler for each button. Events bubble up so you'll be able to catch the event and figure out which button it originated from. This helps speed up your overall code and makes your JavaScript more responsive.

23. Gracefully degrading

Ensure that your web design enable gracefully degrading which means that your design should do it in a way that allow older browsers to be used or letting users disable particular features, can "step down" to a method that still allows access to the basic content of the site, though perhaps not as snazzy in appearance.

24. Optimize Images

This is quite clear cut. Always optimize your image so that your pages load faster. Although images are the last one to be render. It is still equally important that your site load faster.

25. Post-load Component

Not all scripts or elements are necessary. Post-load component means postpone the loading to a later point of time. An example will be an image gallery, allowing the smaller image to be loaded up first as they are smaller and post-load all larger image. This way, user will get to see all the images which provide a better user experience.  All necessary things to render the page should be loaded and all other not so important element shall be post loaded. Since browser has a limitation on the number of files retrieve per domain, it is best for it to retrieve all the important things first.

26. Never Scale Images in HTML

If your image is size 10 render it as size 10. Scaling it on the browser will not only damage the overall display of your site. It also required more processing power from the browser which in reason in slower rendering of your website.

27. Avoid Filters

If you are using AlphaImageLoader filter to fix a problem with semi-transparent true color PNGs on earlier version of IE 7. Then you should stop as it blocks rendering and freeze the browser while the image is being downloaded.

28. HTML advertisements.

If you display advertisements on your website, you may notice a decrease in load speed if you are using JavaScript ads. Consider opting for HTML ads instead.

29. Use the PNG format for images

PNG image files are smaller and render better. Furthermore, quality is better in compare to gif and jpeg. Of course, PNG image also has its own disadvantages.

30. Error Free

Ensure that both JavaScript and CSS contain no or minimum error. So that the browser will not have to do additional stuff due to some error occurs in your code.

31. Remove anything you don't need

Especially in JavaScript and CSS. Often there are extra lines of code that are redundant.  It is best to check!

32. Use Shorthand Notation.

If you don't practice this in CSS, I think you better should as shorthand notation is another way of optimizing CSS files.

33. Tile your backgrounds

Using a small background image and make it repeats in x and y axis will help reduce a lot of download times which make your website render faster.

34. Opt for CSS rollovers

If you are a pure programmer and meet JavaScript framework, you will most likely write your animation on your element. It is best to use what is already in the browser than trying to recreate something that is available. Use CSS hover method instead which reduce both JavaScript and CSS code!

35. Use CSS instead of tables for layout

Using table to layout your site have many disadvantages over layout with CSS. The most obvious one is that there is more HTML element on your page which increases both download and render work. The other disadvantage is the difficulty of maintenance by human being. Trust me I have been there before.

36. Consistency

Write your HTML element in lower case. Browser is not very smart when they differentiate between