You can use this code:

function scrollToLine($textarea, lineNumber) {
  var lineHeight = parseInt($textarea.css('line-height'));
  $textarea.scrollTop(lineNumber * lineHeight);      
}

Some caveats about this code:

1. Your textarea needs to have a line-height in Pixels.
2. The code will scroll to the line number in the text area, not the line number of the original text. These will differ if any lines wrap at the edge of the textarea.

Also see our solution for [scrolling a textarea to a given position with jQuery](htt...

zClip is a lightweight jQuery "copy to clipboard" plugin built using the popular Zero Clipboard library. This plugin uses an invisible Adobe Flash movie that is fully compatible with Flash Player 10 and below.

KeyboardJS is a library for binding to keys or key combos

Cross-Origin Resource Sharing (CORS) is a browser technology specification, which defines ways for a web service to provide interfaces for sandboxed scripts coming from a different domain under same origin policy. CORS is a modern alternative to the JSONP pattern. While JSONP supports only the GET request method, CORS also supports other types of HTTP requests. Using CORS enables a web programmer to use regular XMLHttpRequest which supports better error handling than JSONP. On the other hand, JSONP works on legacy browsers that do not have C...

jQuery

You can say:

$(element).is(':visible')

and

$(element).is(':hidden')

jQuery considers an element to be visible if it consumes space in the document. For most purposes, this is exactly what you want.

Native DOM API

Emulate jQuery's implementation :

element.offsetWidth > 0 && element.offsetHeight > 0;

jQuery > 3

Query 3 slightly modifies the meaning of :visible (and therefore of :hidden).

Emulate jQuery'...

An alert alternative for jQuery that looks good. Apprise is a very simple, fast, attractive, and unobtrusive way to communicate with your users. Also, this gives you complete control over style, content, position, and functionality. Apprise is, more or less, for the developer who wants an attractive alert or dialog box without having to download a massive UI framework.

There is no way to do it. This behavior is by design. You lose.

"Wallaby" is the codename for an experimental technology that converts the artwork and animation contained in Adobe® Flash® Professional (FLA) files into HTML. This allows you to reuse and extend the reach of your content to devices that do not support the Flash runtimes. 

The difference between .bind(), .live(), and .delegate() is not always apparent. Having a clear understanding of all the differences, though, will help us write more concise code and prevent bugs from popping up in our interactive applications.

jQuery's selector engine, live()-like event handlers, pixel-perfect layout measuring.

This is non-trivial because you need to fake event objects and require different code for different browsers. Luckily, there is tool support for most types of events.

In jQuery you can say:

$('a#close_window').click();

In Prototype you can use event.simulate.js from the Protolicious library to say:

$$('a#close_window')[0].simulate('click');

To trigger custom events with Prototype, you can use the [built-in Element.fire()](http://api.prototypejs.org/dom/...

Thanks to habits engrained by Rails 2’s link_to_remote and remote_form_for, we expect that Rails 3 would also handle the AJAX response for our remote links and forms. But it doesn’t; it leaves that for you.

The timepicker addon adds a timepicker to jQuery UI Datepicker, thus the datepicker (jQueryUI) is required for using any of these. In addition all datepicker options are still available through the timepicker addon.

Captify is a plugin for jQuery written by Brian Reavis (@brianreavis) to display simple, pretty image captions that appear on rollover

WMD is a simple, lightweight HTML editor for blog comments, forum posts, and basic content management. You can add WMD to any textarea with one line of code. Add live preview with one line more. WMD works in nearly all modern browsers, and is now completely free to use.

With this plugin, you can create a scalable tooltip by just using a single background image for the tooltip body.

Use this if you want to show or hide part of a form if certain options are selected or boxes are checked.

The triggering input gets an data-selects-visibility attribute with a selector for the elements to show or hide, like

<%= form.select :advancedness, [['basic', 'basic'], ['advanced', 'advanced'], ['very advanced', 'very_advanced]], {}, :"data-selects-visibility" => ".sub_form" %>

The elements that are shown/hidden look like

<div class="sub_form" data-show-for="basic"> 
  only shown for advancedness = basic 
</div>

...

PaintbrushJS is a lightweight, browser-based image processing library that can apply various visual filters to images within a web page.

JSViz makes it easy to create dynamic 2D views of information. Practical applications include network graphs, navigation, and other dynamic layouts.

The Sexy Curls jQuery Plugin is an open-source jQuery plugin by Elliott Kember which lets you share in the beauty of the page fold.

A simple web-based WYSIWYG editor, written in MooTools.

scriptaculous replacement

HotKey provides functionality similar to the accesskey attribute, but has many enhancements that allow for more granular control when creating keyboard driven interfaces.