7 tips for for loading Javascript rich Web 2.0-like sites significantly faster

Introduction

When you create rich Ajax application, you use external
JavaScript frameworks and you have your own homemade code that
drives your application. The problem with well known JavaScript
framework is, they offer rich set of features which are not always
necessary in its entirety. You may end up using only 30% of jQuery
but you still download the full jQuery framework. So, you are
downloading 70% unnecessary scripts. Similarly, you might have
written your own javascripts which are not always used. There might
be features which are not used when the site loads
for the first time, resulting in unnecessary download during
initial load. Initial loading time is crucial – it can make
or break your website. We did some analysis and found that every
500ms we added to initial loading, we lost approx 30% traffic who
never wait for the whole page to load and just close browser or go
away. So, saving initial loading time, even by couple of hundred
milliseconds, is crucial for survival of a startup, especially if
it’s a Rich AJAX website.

You must have noticed Microsoft’s new tool "Doloto download optimizer" href=
"http://research.microsoft.com/en-us/projects/doloto/">Doloto

which helps solve the following problem:

Modern Web 2.0 applications, such as GMail, Live Maps, Facebook
and many others, use a combination of Dynamic HTML, JavaScript and
other Web browser technologies commonly referred as AJAX to push
page generation and content manipulation to the client web browser.
This improves the responsiveness of these network-bound
applications, but the shift of application execution from a
back-end server to the client also often dramatically increases the
amount of code that must first be downloaded to the browser. This
creates an unfortunate Catch-22: to create responsive distributed
Web 2.0 applications developers move code to the client, but for an
application to be responsive, the code must first be transferred
there, which takes time.

Microsoft Research looked at this problem and published
"http://research.microsoft.com/en-us/projects/doloto/fse08.pdf">this
research paper in 2008
, where they showed how much improvement
can be achieved on initial loading if there was a way to split the
javascripts frameworks into two parts – one primary part
which is absolutely essential for initial rendering of the page and
one auxiliary part which is not essential for initial load and can
be downloaded later or on-demand when user does some action. They
looked at my earlier startup "http://www.pageflakes.com">Pageflakes and reported:

2.2.2 Dynamic Loading: Pageflakes
A contrast to Bunny Hunt is the "Pageflakes Web 2.0 start page" href=
"http://www.pageflakes.com">Pageflakes
application, an
industrial-strength mashup page providing portal-like
functionality.
While the download size for Pageflakes is over 1 MB, its
initial
execution time appears to be quite fast. Examining network
activity
reveals that Pageflakes downloads only a small stub of code
with the initial page, and loads the rest of its code dynamically
in
the background. As illustrated by Pageflakes, developers today
can
use dynamic code loading to improve their web application’s
performance.
However, designing an application architecture that is
amenable to dynamic code loading requires careful consideration
of JavaScript language issues such as function closures,
scoping,
etc. Moreover, an optimal decomposition of code into
dynamically
loaded components often requires developers to set aside the
semantic
groupings of code and instead primarily consider the execution
order of functions. Of course, evolving code and changing
user workloads make both of these issues a software maintenance
nightmare.

Back in 2007, I was looking at ways to improve the initial load
time and reduce user dropout. The number of users who would not
wait for the page to load and go away was growing day by day as we
introduced new and cool features. It was a surprise. We thought new
features will keep more users on our site but the opposite
happened. Analysis concluded it was the initial loading time that
caused more dropout than it retained users. So, all our hard work
was essentially going to drain and we had to come up with something
ground breaking to solve the problem. Of course we had already
tried all the basic stuffs – "IIS 6 compression setup quick and easy way" href=
"http://msmvps.com/blogs/omar/archive/2006/08/10/iis-6-compression-quickest-and-effective-way-to-do-it-for-asp-net-compression.aspx">
IIS compression
, "Making best use of cache for faster page loading" href=
"http://msmvps.com/blogs/omar/archive/2006/08/10/iis-6-compression-quickest-and-effective-way-to-do-it-for-asp-net-compression.aspx">
browser caching
, "Ensure - loading javascript, css, html on demand" href=
"http://www.codeplex.com/ensure">on-demand loading of JavaScript,
css and html
when user does something, "Deferred Javascript Execution" href=
"http://ajaxian.com/archives/gmail-mobile-latency">deferred
JavaScript execution
– but nothing helped. The frameworks
and our own hand coded framework was just too large. So, the idea
tricked me, what if we could load functions inside a class in two
steps. First step will load the class with absolutely essential
functions and second step will inject more functions to the
existing classes.

I published a codeproject article which shows you 7 tricks to
significantly improve page load time even if you have large amount
of Javascript used on the page.

"7 Tips for Loading JavaScript Rich Web 2.0-like Sites Significantly Faster"
href="http://www.codeproject.com/KB/ajax/fastjavascript.aspx">7
Tips for Loading JavaScript Rich Web 2.0-like Sites Significantly
Faster

  1. Use Doloto
  2. Split a Class into Multiple JavaScript Files
  3. Stub the Functions Which Aren’t Called During Initial Load
  4. JavaScript Code in Text
  5. Break UI Loading into Multiple Stages
  6. Always Grow Content from Top to Bottom, Never Shrink or
    Jump
  7. Deliver Browser Specific Script from Server

If you like these tricks, please vote for me!

9 Comments

  1. 7 tips for for loading Javascript rich Web 2.0-like sites significantly faster - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5

    Thank you for submitting this cool story – Trackback from DotNetShoutout

  2. Daily tech links for .net and related technologies – September 26-28, 2009 Web Development 10 Things

  3. Question if I run my website on:

    http://localhost:8888 and I run the tool I get an message:

    NotifyUser: Fiddler Port in Use – Unable to bind to port

    And If I do it in other order then I get the message in Visual Studio that the port is allready in use.

    What am I doing wrong?

    Thanks,

    Bjorn

  4. Such a useful tips for JAVA people, it's contain all related to the JavaScript, so it's amazing and it's very important to every body…

  5. Thank you for submitting this cool story – Trackback from PimpThisBlog.com

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