From wiki:
A JavaScript library is a library of pre-written JavaScript which allows for easier development of JavaScript-based applications, especially for AJAX and other web-centric technologies.
History
Main article: JavaScript: History
While JavaScript, as first developed by Netscape (and later Mozilla), has long had a presence on the Web for many websites, it gained a particular pitch with the rise of the Web 2.0 era of computing, in which JavaScript became increasingly used for the development of user interfaces for applications, both web-based and desktop-based.
JavaScript was also combined with CSS to create dynamic web pages, which have also become popular as a more efficient and accessible alternative to Flash-based websites.
Libraries
With the expanded demands for JavaScript, an easier means for programmers to develop such dynamic interfaces was needed. Thus,
and
allowing for developers to concentrate more upon more distinctive applications of Ajax. This has led to other companies and groups, such as Microsoft and Yahoo! developing their own JavaScript-based user interface libraries, which find their way into the web applications developed by these companies.
Some JavaScript libraries allow for easier integration of JavaScript with other web development technologies, such as CSS, PHP, Ruby, and Java. Many libraries include code to detect differences between runtime environments, and remove the need for applications to allow for such inconsistencies.
Almost all JavaScript libraries are released under either a copycenter or copyleft license to ensure license-free distribution, usage, and modification.
Frameworks[edit]
Some JavaScript libraries, such as YUI, are classified as frameworks since they exhibit full-stack capabilities and properties not found in general JavaScript libraries.
