Java Reference
In-Depth Information
JavaScript
The language we'll be learning in this topic is
JavaScript
, often referred to as the language
of the Web. Nearly all web browsers can run JavaScript, making it one of the most popular
programming languages in the world. It has a low barrier to entry―all you need to program
in JavaScript is a text editor and a web browser. Although it is easy to get started, JavaScript
can be a tricky language to grasp as it has some unique features and interesting quirks. Once
you have mastered it, though, you'll find it is a very flexible and expressive language that
can create some powerful applications.
JavaScript is a high-level language that is compiled at run time. This means that it requires
an engine that is responsible for interpreting programs and running them. The most common
JavaScript engines are found in browsers such as Firefox, Chrome, or Internet Explorer, al-
though JavaScript can be run without a browser. Many modern JavaScript engines use a
Just-in-time (JIT) interpreting process, which considerably speeds up the compilation pro-
cess, making the programs run faster.
JavaScript is also a dynamic language, which means that elements of a program can change
while it is running.
The History of JavaScript
The World Wide Web was originally a bunch of pages linked together by hyperlinks. Soon
people wanted more interaction and so Netscape (an early browser vendor) asked Brendan
Eich to develop a new language for their Navigator browser. This needed to be done quickly
because of the intense competition between Netscape and Microsoft to be first to market,
and Eich managed to create a prototype language in just ten days. In order to do this, he bor-
rowed various elements from other languages, including AWK, Java, Perl, Scheme, Hyper-
Talk, and Self. The new language was originally called LiveScript, but was hastily rebranded
as JavaScript so that it could benefit from the publicity that the Sun Microsystem's Java lan-
guage was attracting at the time. This name has often caused some unfortunate confusion,
with JavaScript often thought of as a lighter version of Java; the two languages are unre-
lated, although JavaScript does share some syntax with Java.
JavaScript made its debut in version 2 of Netscape's Navigator browser in 1995. The follow-
ing year, Microsoft reverse-engineered JavaScript to create their own version, called JScript
to avoid copyright issues with Sun Microsystems who owned the Java trademark and had
