Tag Archives: Javascript/jQuery

Excellent videos to get you started with CouchDB

Published Jun 17, 2010 | In Database Programming, Javascript/jQuery

Excellent videos to get you started with CouchDB

Okay, I got to admit. My latest crush is CouchDB. :)

I found lot of people referring to CouchDB when they were talking about node.js which made to find out more about CouchDB. I read a couple of articles and then came to know that O’Reilly was having a webcast (in fact two), in which Chris Anderson, one of the core committers of CouchDB explains about it. I thought of posting the videos here, so that even you could get hooked up to CouchDB ;)

Introduction to Apache CouchDB

This is part one of the webcast. In this webcast, Chris gives a technical overview. He also describes some of CouchDB’s existing users. This webcast also had a question and answer session where Chris answered user’s questions.

You can either view them as an Adobe Connect Pro archived recording or in youtube. I have embedded the youtube video below for quick viewing


Writing jQuery CouchApps

This is part two of the webcast. In this webcast, Chris shows how to hack JQuery CouchApps, which is a p2p web applications that can be deployed anywhere there’s a couch DB.

You can either view them as an Adobe Connect Pro archived recording or in youtube. I have embedded the youtube video below for quick viewing.


CouchDB to the edge (JSConf)

This is a talk which Chris Anderson and Jan Lehnardt gave in JSConf 2009 titled “CouchDB to the edge”. They give a nice introduction to CouchDB and also explain about how to write offline web apps that can synchronize the data once they are online.

You can view the video in blip.tv. I have embedded it below for easy viewing.


What’s new in CouchDB 0.11 and 1.0

This is an upcoming webcast (again by O’Reilly) which will happen on June 22, 2010.

In this webcast, Jan Lehnardt will be talking about the new features that will be coming up in the latest version of CouchDB like Views, Replication, Authentication, Virtual Hosts and the Rewriter etc.

You can register for the webcast at the webcast’s homepage.

I will also try to embed the video of this webcast once it is published till then happy couching ;)

Update

Videos from the latest O’Reilly are up now.

You can either view them as an Adobe Connect Pro archived recording or in youtube. I have embedded the youtube video below for quick viewing.

Posted in Database Programming, Javascript/jQuery | Tagged , , , | 2 Comments

jQuery.later – a setTimeout wrapper in jQuery

Published Mar 27, 2010 | In Javascript/jQuery

jQuery.later – a setTimeout wrapper in jQuery

Recently I have been playing around with YUI 3 and found that it had a nice wrapper for setTimeout/setInterval which nicely encapsulated it.

I thought it would be nice to have a wrapper like that for jQuery, which led to this nice little Plugin for jQuery called jQuery Later

Download

You can download it from my github page. It also includes a html page which tells you how to use it.

Syntax

jQuery later function follows the same syntax as that of YUI.

jQuery.later ( when , o , fn , data , periodic )

Executes the supplied function in the context of the supplied object ‘when’ milliseconds later. Executes the function a single time unless periodic is set to true.

Parameters:
when <int> the number of milliseconds to wait until the fn is executed.
o <object> the context object.
fn <Function|String> the function to execute or the name of the method in the ‘o’ object to execute.
data <object> [Array] data that is provided to the function. This accepts either a single item or an array. If an array is provided, the function is executed with one parameter for each array item. If you need to pass a single array parameter, it needs to be wrapped in an array [myarray].
periodic <boolean> if true, executes continuously at supplied interval until canceled.
Returns: object
a timer object. Call the cancel() method on this object to stop the timer.

License

Released under MIT License

PS: BTW this is my first jQuery Plugin. :)

Posted in Javascript/jQuery | Tagged , , | 5 Comments

Find duplicates values in a set of textboxes using jQuery

Published Sep 2, 2009 | In Javascript/jQuery

Find duplicates values in a set of textboxes using jQuery

Well sometime back, I faced this unique problem. It took me sometime to solve it, so I thought of documenting it as my learning so that it is useful for others and might help me one when I need to do it again.

Problem

Okay, the following is the requirement. You have a web page with a set of text boxes. The number of text-boxes might vary based on some backend logic. You need to make sure the user doesn’t enter duplicate values in these set of textboxes. He can leave them blank, but cannot enter duplicate values.

Solution

The following is my solution.

function findDuplicates() {
    var isDuplicate = false;
    jQuery("input[name^='access_keys']").each(function (i,el1) {
        var current_val = jQuery(el1).val();
        if (current_val != "") {
            jQuery("input[name^='access_keys']").each(function (i,el2) {
                if (jQuery(el2).val() == current_val &amp;&amp; jQuery(el1).attr("name") != jQuery(el2).attr("name")) {
                    isDuplicate = true;
                    jQuery(el2).css("background-color", "yellow");
                    jQuery(el1).css("background-color", "yellow");
                    return;
                }
            });
        }
    });
 
    if (isDuplicate) {
        alert ("Duplicate values found.");
        return false;
    } else {
        return true;
    }
}

I basically loop through all the text boxes and compare the values with all the other textboxes, in nested loops. Basically it is like bubble sort. I know this is bad, but was not able to think of any efficient way of doing it. Do you guys can think of a better way?

Posted in Javascript/jQuery | Tagged , , | 1 Comment

Evangelizing jQuery

Published Feb 27, 2009 | In Javascript/jQuery

Evangelizing jQuery

Regular readers of this blog will know that I am great fan of jQuery. Recently I am thinking of evangelizing jQuery at work and convince people who take up decision to make jQuery as the default JavaScript framework to be used across the organization.

The following is the list of advantages/benefits which I have prepared so far. 

  • Light weight and has a very small footprint.
  • Browser abstraction – jQuery provides browser abstraction and is hightly optimized for each individual browser.
  • Excellent Plugin architecture – jQuery has an excellent Plugin architecture and you can find a jQuery Plugin for anything that you want to do.
  • Speed – When compared with other libraries, jQuery is much faster.
  • Less code == Less mistakes == better performance.
  • Active development community – It has a very active development community headed by John Resig
  • Backed by major organizations like Microsoft and Nokia. Microsoft had integrated it with the latest version of ASP.NET
  • Very small learning curve.
  • Chaining well suited for designers since it uses selectors based on CSS Selectors.
  • Excellent Documentation for all methods and selectors.
  • jQuery UI – Provides ready made themable GUI components.

Let me know if you could think of any addition to this list. Thanks :)

Posted in Javascript/jQuery | Tagged , | 4 Comments

Notes for “DOM is a mess” by John Resig

Published Feb 6, 2009 | In Javascript/jQuery

Notes for “DOM is a mess” by John Resig

I just finished viewing John Resig’s talk titled “DOM is a mess” at Yahoo. I took some notes while watching the video and I am posting them here, so that I can refer to them at a later point of time (It is easier to search when it is not on paper :) ). Also it might help someone to get the outline of the talk before actually watching the video. The original video runs for more than an hour.

Also be warned that the following is my own interpretation of the video and I might have missed or could have interpreted some point differently. :)

About the speaker, John Resig

As you all know John Resig is the creator of the excellent jQuery library. He works for Mozilla corporation and you can get more information about him from his blog.

DOM is a mess

This is the first thing John Resig said about DOM methods after saying that DOM is a messy

Nearly every DOM method is broken in some way, in some browser.

The following are some of the bugs in the DOM methods

getElementByID ()

IE and Old versions of Opera return elements whose name == id

getElementByTagName ()

.length gets overwritten in IE if an element with an ID = “length” is found

getElementsByClassName ()

Opera doesn’t match a second specified class

querySelectorAll ()

Safari 3.2 can’t match uppercase characters in quirks mode.

So the moral is that almost every method in DOM is messed up.

Writing Cross-browser code

Find out the cost/benefit ratio for supporting a browser and then pick the browsers you are going to support before writing your code.

He talked about Yahoo’s graded support and jQuery browser Support.

Escaping from DOM’s mess

The following are some of the tips to escape from DOM’s mess.

  • Having a good test suite is not a facility but a requirement.
  • Don’t introduce global variables or extend native objects.
  • The order in which style sheets are included matters.
  • Don’t use browser sniffing, but use Object detection or feature simulation instead.
  • Don’t assume a browser will always have a bug. They might get fixed in a future release.
  • Gracefully degrade for old browsers
  • As your code matures, the number of assumptions should reduce.
  • While removing elements from DOM, clean it by unbinding the events

Links

So my dear readers what you think about my notes. Also let me know if you like notes for videos in this format. If there is a demand, then I can post some of my notes on other videos which I have already viewed.

Posted in Javascript/jQuery | Tagged , , , , , | 1 Comment

Useful jQuery links

Published Mar 6, 2008 | In Javascript/jQuery

Useful jQuery links

I found lot of useful links related to jQuery while researching for my presentation on jQuery. I thought of sharing them here so that it will be useful for others who are looking to get their feet wet with jQuery.

I am planning to constantly updated this post, so if you have any other links which might be useful do leave a comment and I will add them.

Homepage

References

Tutorial/Articles

jQuery related slides

Some useful Plugins

jQuery Related Books

Posted in Javascript/jQuery | Tagged , , | 4 Comments

getElementsByTagName and the sort order of the result array

Published Sep 16, 2006 | In Web Programming

getElementsByTagName and the sort order of the result array

I was just wondering how the result array of the getElementsByTagName function will be sorted. Will it be elements of the array be sorted in the order in which they appear in the document or is it completely random? And how does it behave in different browsers?

Can anyone shed more lights on this or provide me some pointers?

Self Note (by my evil twin): Sudar, you have become lazier these days. If you are not getting a response take the pain to test it across different browses by yourself!!

Posted in Web Programming | Tagged , , | 2 Comments

What is your Level of web knowledge?

Published Jun 4, 2006 | In Web Programming

What is your Level of web knowledge?

Well I am going to flirt with an Internet Meme which is getting spread around. It all started when Emil wrote Levels of CSS knowledge. This inspired Roger to write Levels of HTML knowledge and that got followed by Levels of Javascript knowledge, the levels of Accessibility knowledge etc.

Instead of leaving a comment on each blog separately I decided to write about my level of knowledge here. So here it goes

Apart from letting you know where you are standing, these posts are really fun to read. So what is your Level of web Knowledge?

Posted in Web Programming | Tagged , , , , | Leave a comment

JavaScript Components

Published Nov 9, 2004 | In Javascript/jQuery

JavaScript Components

Check out yxScripts.com. Excellent ready to use java script components like Menu, calendar etc.. Really damn good.

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JavaScript Toolbox

Published Nov 4, 2004 | In Javascript/jQuery

JavaScript Toolbox

JavaScript Toolbox – Reusable Libraries And Objects

This is a collection of Javascript source files, examples, and concepts. Use these instead of always re-inventing JavaScript solutions.

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