JScript: What is it?
VBScript may be better known, but JScript, Microsoft's other
scripting language, is used widely in Active Server Pages (ASP)
programming, and system automation and administration tasks. Along
with its open source counterpart Javascript, JScript has evolved
from a browser-dependent way of controlling web pages to a fully
independent language used in server as well as client-side
applications.
JScript has kept its scripting feel and is a fairly forgiving
language that can be used by non-programmers and beginners, as well
as for "quick and dirty" coding. But over the years it has acquired
increasingly sophisticated object-oriented and other modern
language features. JScript.net combines classic JScript
compatibility with access to the resources of the .net Framework
Where did it originate?
In 1995 Netscape came up with a scripting language designed to be
used with its Navigator browser. Its name was changed from Livewire
to Javascript because its syntax resembled Java.
The browser wars were at their height, and in a bid to get its
language established as an open standard, Netscape handed it over
to the European Computer Manufacturers Association (Ecma).
Microsoft followed with an Internet Explorer implementation,
JScript. JScript and Javascript share an agreed core of
functionality based on Ecmascript which, like other standards
body-driven languages, has long intervals between releases.
Mozilla (which took over Netscape's products) has a version of
Javascript for Java called Rhino.
What is it for?
Scripting languages were originally devised to enable web
developers to make their pages more interactive. They can be used
for automating routine administration tasks, obtaining feedback
from users and updating records with the output of user visits.
But as users have become comfortable with them - and the languages
acquire more sophisticated functionality - JScript and Javascript
are used increasingly in large and complex applications.
What makes it special?
JScript.net supports different levels of programming ability. As
Microsoft puts it, "One of the defining qualities of a script
language is the ability to write code without having to worry about
the types of variables. Making types optional allows developers to
leverage their existing JScript skills and source code, while
providing a smooth migration path for adding types to new and
existing programs." Microsoft also claims that as a compiled
language, JScript offers performance comparable to C# and Visual
Basic .net.
How difficult is it to master?
Javascript and JScript were devised to enable HTML authors, who are
not necessarily trained programmers, to embed snippets of code in
their pages. The syntax has been kept simple, and the more
demanding functionality is optional. Familiarity with Java or C++
can help.
Many users take advantage of the thousands of scripts freely
available on the web, without ever formally learning how to use
JScript or Javascript.
Where is it used?
JScript is used widely in ASP development, web design and systems
administration.
What systems does it run on?
In general, JScript is used with Microsoft technologies and
Javascript with everything else, but the skills are essentially
portable and interchangeable.
What is coming up?
Ecmascript version 4, the first major revision since 1999, on which
the next releases of JScript and Javascript will be based.