Are there any drawbacks to using head.js? - javascript

Things I am aware of:
Screen flicker if scripts alter styles / content (not an issue for me as I currently load scripts at the end of the page and so have workarounds already)
Inability to detect script load failure (not too concerned about this either as everything I develop is required to work with or without javascript. Might affect my workarounds for item 1 but happy with this risk)
It looks to be a very good option to me but I am hoping for some references (feel free to say only positive things!) before I invest time in incorporating it into my next project.
Currently we develop mid-to-large sized sites with, generally, a moderate amount of Javascript (although this is growing rapidly). We also use the jQuery library for the bulk of our Javascript.
Anyone have any experience? Good or bad! :)
P.S. for those interested this is head.js

Nope. As long as you put any code that is dependent on the loading files inside head.ready {} then you will not face any problems with your code.

Here is my conclusion for head.js, I have done some benchmarks myself:
http://blog.feronovak.com/2011/03/headjs-script-is-it-really-necessary.html
It is subjective opinion and benchmarks are not by any means scientific.

I was/am interested and thinking of maybe also using head.js BUT i found something not so nice: In the url that you gave me there are three tab buttons:
SCRIPT SCRIPT SRC head.js
SRC in head on bottom on head
Shift+Ctr+Refresh gives very little differences for me (+/-10ms between the three # 120mbit line, firefox 3.6.13)
When I use Ctr+R refresh, the results on the head.js are consistently 100ms slower than the other two versions without head.js... So, its NOT always faster.

There would be no problem on using jquery or javascript library heavily. Try to main each library as unique.
I am using prototype, scriptaculous, jquery and many more jquery additional plugins. I faced an error while loading entire scripts. Then i found out its due to $ sign which is an important parameter of jquery and prototype.
i had used
$.noConflict();
jQuery(document).ready(function($){
//jquery codes here
})
So keep your script library unique

head.js() gave a problem to my pages. None of my asp:button OnClick events were working. But if I include the scripts in the traditional way (<script type="text/javascript src="") then the events worked perfectly. I tried EnableClientScript = "false" and also CausesValidation="false". But nothing worked. Finally just scrapped the head.js idea since it did not make a lot of difference to my page load time, anyway.

Related

All scripts AND libraries in ONE js script?

Ok so I am in the process of building my first Javascript 'framework' or 'bootstrap' which will be implemented in combination with a single pre-processed CSS file. I am gathering my favorite content slider, smooth scroller, content slideshow, parallax elements & bg-img, sticky elements, among a few more cutting edge navigational & UI based scripts (cross-browser/platform/device/viewport compatibility and performance). My problem is when constructing my demo page with all combined elements in place loaded and active on the page... well many seeem to require a different version of Jquery to be called in order to function properly. I have managed to get them to work properly while testing by carefully reordering the jquery librarys as they are called in the of the page. Now here is my (2) part question:
How do I get all my JQuery to work properly without loading multiple versions of it (one for each script almost)
I have a sample in my portfolio which I would love to use as the example. http://www.nicholasabrams.com/ (non mobile device version). In the src for that URL you will see only (1) js and (1) css - including the jquery libraries which are ALSO included in the single .js in the begining of the file. Please don't flame me, as I am asking for help. The link above works fine now (with apple as a slight exception)... but I am just trying to eliminate any bad practices I have as I have just started as a web developer at my first large company. Thanks!!
PS: Would post a snippet but its quite a large js file as you would imagine but if you will, please inspect my src and let me know what you think because my sites first load decreased from 22 seconds to 4-7 seconds after doing the above I wish I could just include the latest version of JQuery!)
if I understand you correctly you are loading more than one jQuery library to the page (in different order)? That's a mistake - you shouldn't do that.
What you should do is make sure that the plugins you work with are compatible with the library you are working with. If they're not - wither find other plugins or fix the ones you have to support the jQuery language you are using.
You have a 2 megabyte hi-res background image, that is insane! I would scrap that and the swirl image, while it may look cool to you, it is distracting and may actually make people want to avoid your website. It makes it difficult to concentrate on the text in the middle of your screen. You don't want people to remember the swirling image, but rather your portfolio, right?
You also have 404's on the following:
http://www.nicholasabrams.com/ScrollSpy_files/result-light.css
http://www.nicholasabrams.com/example-images/testing_station.png
404's are bad for several reasons, they are a wasted resource as they slow the loading of your page, because it attempts to find something and does not find it, and, finally, they have a negative impact on your SEO, specifically Google PageRank docks you for any 404's.
Find a way to work with one version of jQuery, it will eventually bite you to have multiple versions of the library and it is a bandwidth killer to have your users load up a bunch of libraries, even if they are CDN'd.

Is it considered Bad Idea to Edit the orginal JQuery File?

We have Tabs-Menu controls which rely on jQuery library and the dev-manager insist that i should get the functions that controls are using into a separate java-script file so we don't have to reference/rely on the whole jQuery, so it made me wonder.. is it a bad idea to edit the jQuery files ?
Yes it is a very bad idea. It would be a nightmare to maintain with all the bug fixes and feature changes the jQuery team would make.
You should write plugins to modify the behavior as you want.
The gzipped production version of jQuery is 31K. Not only is this an unmaintainable idea, but this is a pre-optimization. Any images beyond tiny PNGs or GIFs will likely be as large or larger than the entire jQuery library.
Additionally, this is time that could be spent addressing actual problems. I don't know what sort of userbase you're targeting, but unless every one of your users is on dialup, 31K will take no time at all to download.
is it a bad idea to edit the jQuery files ?
Yes. If you edit the core jQuery library, you make it much more difficult to use future versions of jQuery, which may include important new features, bug fixes, etc. If you make your changes in plugins, as you should, you can just drop in the new versions of jQuery when they're released.
Well I'd say it's a pretty bad idea. You really want the responsibility of maintaining the mess you have left after chopping it out? Are you an expert on the jQuery library? Do you understand all of the side effects? You would be better off rewriting portions of your Tabs-Menu controls without jQuery than trying to chop out bits of jQuery. I presume that the issue is that you don't want the "overhead" of including a relatively large script for a small set of features. This is unfortunately the way of jQuery. Either
Accept that you have to use jQuery, and make the most of having it referenced
Rewrite your Tabs-Menu controls without jQuery
any other option is going to be painful. Insist that your dev-manager reads the answers to the question.

Custom jQuery UI

I wanted to use some functionality in jQuery-UI. So, I downloaded a custom version of the same from jQuery website, including only those things in my download that were needed by me. This was supposed to trim down the total size of my page, but to my surprise, the page size remained almost the same even after following the procedure provided at jQuery website.
Did I do something wrong? Or is this the expected behaviour?
You should have a look at JQuery UI Packager, it lets you pick what functionality you want.
It bundles it up with both a custom and a minified JQuery.
When I tried it, I removed everything but core functionality, and it ended up 15kb uncompressed.
Then I tried it without removing anything, it ended up 206kb uncompressed.
If you're that concerned you should think about gzipping.
Look at this chart of filesizes and how they improve with the different methods.
Here's a post about a guy asking a similar question, and the answer explains what you should focus on.
Here's a discussion about gzip and minify.

Simple lightbox feedback form? Included screenshot

There are so many lightboxes to choose from, I'm looking for a very lightweight one to use in an embedded javascript widget that would be a single domain name. I saw the perfect one on chainreactioncycles.com, it popped up out of nowhere so I took a screenshot:
I tried looking for info on it on the page source, but couldn't find anything that would let me trace where it came from... Would anybody know of one like this? Or exactly that one?
If not exactly like above, anything similar would be great too, keeping the following in mind:
Very small javascript download (animation not needed)
Self contained, not dependent on any libraries other than jquery (since I'm already using that anyway).
Works in major browsers
Close button (like GetSatisfaction or UserVoice)
Dims background
Avoids javascript namespace conflicts (or can easily be made to avoid them)
CSS styling of lightbox does not interfere with site styling
Have you used an existing lightbox scripts for this same purpose with similar requirements? Did you roll your own? Insights welcome!
What you are looking for is called a modal box.
Here is a list of them
... and here is a striking replica of what you are looking for
Check out Zoombox.. It sounds like what you're looking for... Simple to use... Allows custom content.. jQuery Module... From past experience it covers what you have outlined as requirements etc
http://www.grafikart.fr/zoombox will tell you all you need to know.

What are the likely main reasons my website is very slow on IE?

I need to know what can be the main reasons (apart from the basics like grouping CSS selectors, reducing image size, using image sprite etc.) which makes a website slow on Internet Explorer, because my website works fine on the others like FF, chrome etc.
Is it the huge use of Javascript framework (ie. jQuery, extjs, prototype)?
Is it because of the use of plugins based on JS framework?
Should I use core javascript and remove the use of any js framework?
Should I try to avoid using jQuery(document).ready()? in case of jQuery framework?
Above some of the questions which I know and please answer the questions which I couldn't ask because of lesser knowledge about these.
I need to make my website perform well on IE (6,7,8) also please suggest.
Thanks
It has nothing to do with jQuery. The plugins however are hit or miss, and may not be well tested in IE. I'd use at your own risk.
DOM manipulation is very slow in IE. using appendChild (or insertRow) to add multiple nodes (say, 100+ for a long list) is much slower than building a string and doing one innerHTML.
You also want to be careful how you access nodes. Devs tend to rely upon jQuery too much and search for nodes via their class names, like:
$(".evenRows").hover(doSomething);
IE doesn't have a native way of getting a node by class name, so JQ is looping through the entire document and every single element and checking its class name... which needs to be checked via RegExp because it may look like:
class="evenRows yellow foo bar"
Finally, in spite of its improvements, IE8 is still using an old rendering engine - the same as IE6. Don't go crazy with the animations, and don't expect miracles.
As MSIE has a default-limit of 2 simultaneous connections you should minimize the number of requests that are required for building the page(use css-sprites, merge js-and css-files into a single file)
While you need to speed things up in IE, you can still use Firebug to look for places, that consume resources.
Install Yslow and see what it tells you
Run the site under profiler (Yslow or Firebug have one) and look for a bottleneck
It is very difficult to answer general questions like this, but jQuery is unlikely to be the one slowing everything down, just remember to
Use IDs as selectors wherever possible — they are the fastest, i.e. $('#myid')
Avoid using .class selectors without tagname, i.e. $('div.myclass') can be ten times faster than $('.myclass').
and so on
More tips for using jQuery to achieve better performance.
Earlier versions of IE will, in general, run JavaScript slower than later versions of IE, because there have been advances in JavaScript compilation speed since then.

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