JScript

JScript

Appeared in	1996
Developer	Microsoft
Stable release	9.0 (March 2011)
Typing discipline	dynamic, weak, duck
Major implementations	Windows Script, JScript .NET
Influenced by	JavaScript
OS	Microsoft Windows
Usual filename extensions	.js, .jse, .wsf, .wsc (.htm, .html, .asp)
Website	JScript

JScript is a scripting language based on the ECMAScript standard^[1] that is used in Microsoft's Internet Explorer.

JScript is implemented as a Windows Script engine.^[2] This means that it can be "plugged in" to any application that supports Windows Script,^[3] such as Internet Explorer, Active Server Pages, and Windows Script Host. It also means that any application supporting Windows Script can use multiple languages (JScript, VBScript, Perl, and others).

JScript was first supported in the Internet Explorer 3.0 browser released in August 1996. Its most recent version is JScript 9.0, included in Internet Explorer 9.

Another dialect of JScript (as of 2004 - 2006) was JScript .NET, which was based on the yet-unfinished edition 4 of the ECMAScript standard, and can be compiled for the Microsoft .NET platform. JScript.NET, which added several new features to ECMAScript ed. 3, such as optional static type annotations, has been renamed Jscript 10.0.^[4]

Comparison to JavaScript

As explained by JavaScript guru Douglas Crockford in his talk entitled The JavaScript Programming Language on YUI Theater,

[Microsoft] did not want to deal with Sun about the trademark issue, and so they called their implementation JScript. A lot of people think that JScript and JavaScript are different but similar languages. That's not the case. They are just different names for the same language, and the reason the names are different was to get around trademark issues.^[5]

JScript supports conditional compilation, which allows a programmer to selectively execute code within block comments. This is an extension to the ECMAScript standard that is not supported in other JavaScript implementations.

Versions

JScript

The original JScript is an Active Scripting engine. Like other Active Scripting languages, it is built on the COM/OLE Automation platform and provides scripting capabilities to host applications.

This is the version used when hosting JScript inside a Web page displayed by Internet Explorer, in an HTML application, in classic ASP, in Windows Script Host scripts and several other Automation environments.

JScript is sometimes referred to as "classic JScript" or "Active Scripting JScript" to differentiate it from newer .NET-based versions.

Some versions of JScript are available for multiple versions of Internet Explorer and Windows. For example, JScript 5.7 was introduced with Internet Explorer 7.0 and is also installed for Internet Explorer 6.0 with Windows XP Service Pack 3, while JScript 5.8 was introduced with Internet Explorer 8.0 and is also installed with Internet Explorer 6.0 on Windows Mobile 6.5.

Version	Date	Introduced with[6]	Based on[note 1]	Similar JavaScript version
1.0	Aug 1996	Internet Explorer 3.0	Netscape JavaScript	1.0
2.0	Jan 1997	Windows IIS 3.0	Netscape JavaScript	1.1
3.0	Oct 1997	Internet Explorer 4.0	ECMA-262 1st edition[note 2]	1.3
4.0		Visual Studio 6.0 (as part of Visual InterDev)	ECMA-262 1st edition	1.3
5.0	Mar 1999	Internet Explorer 5.0	ECMA-262 2nd edition	1.4
5.1		Internet Explorer 5.01	ECMA-262 2nd edition	1.4
5.5	Jul 2000	Internet Explorer 5.5 & Windows CE 4.2	ECMA-262 3rd edition	1.5
5.6	Oct 2001	Internet Explorer 6.0 & Windows CE 5.0	ECMA-262 3rd edition	1.5
5.7	Nov 2006	Internet Explorer 7.0	ECMA-262 3rd edition + ECMA-327 (ES-CP)[note 3]	1.5
5.8	Mar 2009	Internet Explorer 8.0 & Internet Explorer Mobile 6.0	ECMA-262 3rd edition + ECMA-327 (ES-CP) + JSON (RFC 4627)3	1.5
9.0	Mar 2011	Internet Explorer 9.0	ECMA-262 5th edition	1.8.1

JScript is also available on Windows CE (included in Windows Mobile, optional in Windows Embedded CE). The Windows CE version lacks Active Debugging.

JScript .NET

Main article: JScript .NET

JScript .NET is a Microsoft .NET implementation of JScript, it is a CLS language and thus inherits very powerful features, but lacks many features of the original JScript language, making it inappropriate for many scripting scenarios. JScript .NET can be used for ASP.NET pages and for complete .NET applications, but the lack of support for this language in Microsoft Visual Studio place it more as an upgrade path for classic ASP using classic JScript than as a new first-class language.

Version	Platform	Date	Introduced with	Based on
7.0	Desktop CLR 1.0	2002-01-05	Microsoft .NET Framework 1.0	ECMA-262 3rd edition[note 4]
7.1	Desktop CLR 1.1	2003-04-01	Microsoft .NET Framework 1.1	ECMA-262 3rd edition[note 4]
8.0	Desktop CLR 2.0	2005-11-07	Microsoft .NET Framework 2.0	ECMA-262 3rd edition[note 4]

JScript .NET is not supported in the .NET Compact Framework.

Note: JScript .NET versions are not related to classic JScript versions. JScript .NET is a separate product. Even though JScript .NET is not supported within the Visual Studio IDE, its versions are in sync with other .NET languages versions (C#, VB.NET, VC++) that follows their corresponding Visual Studio versions.

.NET Framework 3.0 and 3.5 are built on top of 2.0 and do not include newer releases of JScript .NET.

(Source: file version of Microsoft.JScript.dll in each framework install)

See also

• Active Scripting
• Chakra (JScript engine)
• ECMAScript, the ECMA International language definition standard which all implementations of this language family must at a minimum follow
• JScript.NET
• JavaScript, Originally LiveScript, it was the first implementation of this language family
• Windows Script File
• Windows Script Host

Notes

1. ^ JScript supports various features not specified in the ECMA standard,^[7] as does JavaScript.
2. ^ Microsoft said JScript 3.0 was "the first scripting language to fully conform to the ECMA-262 standard".^[8]
3. ^ JScript 5.7 includes an implementation of the ECMAScript Compact Profile (ECMA-327) which turns off features not required by the ES-CP when using the "JScript.Compact" ProgID.^{[citation needed]}
4. ^ ^{a b c} JScript .NET is "being developed in conjunction with ECMAScript Edition 4".^[9]

References

1. ^ http://msdn.microsoft.com/en-us/library/hbxc2t98(v=vs.85).aspx
2. ^ http://msdn.microsoft.com/en-us/library/67w03h17(v=VS.85).aspx
3. ^ http://msdn.microsoft.com/en-us/library/shzd7dy4(v=VS.85).aspx
4. ^ What is JScrpt 10.0?
5. ^ Douglas Crockford, The JavaScript Programming Language
6. ^ Version Information (Windows Scripting - JScript), Microsoft, http://msdn.microsoft.com/en-us/library/s4esdbwz.aspx, retrieved 2010-05-31 
7. ^ Microsoft JScript Features - Non-ECMA (Windows Scripting - JScript), Microsoft, http://msdn.microsoft.com/en-us/library/4tc5a343.aspx, retrieved 2010-05-31 
8. ^ Microsoft Embraces ECMA Internet Scripting Standard; Delivers Industry's First ECMA-Compliant Scripting Language, JScript 3.0, In Key Microsoft Products, Microsoft, 1997-06-30, http://www.microsoft.com/presspass/press/1997/Jun97/jecmapr.mspx 
9. ^ What Is JScript .NET?, Microsoft, http://msdn.microsoft.com/en-us/library/xkx7dfw1(VS.71).aspx 

External links

• JScript documentation in the MSDN Library
• JScript 5.7 Release Notes
• JScript .NET documentation in the MSDN Library
• JScript blog
• JavaScript - JScript - ECMAScript version history
• jPaq - A Fully Customizable JScript Library