The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
Active Scripting is the technology used in Windows to implement component-based scripting support. It is based on COM and allows installation of additional scripting engines in the form of COM modules.-Uses and history:The Active Scripting technologies were first released in 1996, with the...
JScript is a scripting language based on the ECMAScript standard that is used in Microsoft's Internet Explorer.JScript is implemented as a Windows Script engine. This means that it can be "plugged in" to any application that supports Windows Script, such as Internet Explorer, Active Server Pages,...
, which, in turn, started life as an implementation of JavaScript
JavaScript
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
.
The primary differences between JScript and JScript .NET can be summarized as follows:
Firstly, JScript is a scripting language, and as such programs
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
(or more suggestively, scripts) can be executed without the need to compile the code first. This is not the case with the JScript .NET command-line compiler, since this next-generation version relies on the .NET Common Language Runtime
Common Language Runtime
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
Common Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
(CIL), formerly called Microsoft Intermediate Language (MSIL), code before it can be run. Nevertheless, JScript .NET still provides full support for interpreting code at runtime (e.g., via the Function constructor or the eval function) and indeed the interpreter can be exposed by custom applications hosting the JScript .NET engine via the VSA interfaces.
Secondly, JScript has a strong foundation in Microsoft's ActiveX
ActiveX
ActiveX is a framework for defining reusable software components in a programming language-independent way. Software applications can then be composed from one or more of these components in order to provide their functionality....
Component Object Model is a binary-interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages...
technologies, and relies primarily on ActiveX components to provide much of its proposal software functionality (including database access via ADO
ActiveX Data Objects
Microsoft's ActiveX Data Objects is a set of Component Object Model objects for accessing data sources. A part of MDAC, it provides a middleware layer between programming languages and OLE DB...
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
to provide equivalent functionality. For backwards-compatibility (or for where no .NET equivalent library exists), JScript .NET still provides full access to ActiveX objects via .NET / COM interop using both the ActiveXObject constructor and the standard methods of the .NET Type class.
Although the .NET Framework and .NET languages such as C# and Visual Basic .NET
Visual Basic .NET
Visual Basic .NET , is an object-oriented computer programming language that can be viewed as an evolution of the classic Visual Basic , which is implemented on the .NET Framework...
have seen widespread adoption, JScript .NET has never received much attention, by the media or by developers. It is not supported in Microsoft's premier development tool, Visual Studio .NET. However, ASP.NET
ASP.NET
ASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages ...
supports JScript .NET.
Language differences
The following are prime examples of language differences between JScript .NET and other .NET languages, including comparisons.
In many programming languages, the main function is where a program starts execution. It is responsible for the high-level organization of the program's functionality, and typically has access to the command arguments given to the program when it was executed....
function that the operating system must call directly when executing a JScript .NET application, as such, JScript .NET program flow is based entirely on global code.
JScript .NET, because of its very loose type checking system can be very easy to learn, since the convention of explicit type declaration is not required at all.
JScript .NET does not require explicit references to the .NET Framework Base Class Library, as certain functions found in earlier versions of JScript, are present in JScript .NET (e.g. functions for finding the tangent
Trigonometric function
In mathematics, the trigonometric functions are functions of an angle. They are used to relate the angles of a triangle to the lengths of the sides of a triangle...
A right triangle or right-angled triangle is a triangle in which one angle is a right angle . The relation between the sides and angles of a right triangle is the basis for trigonometry.-Terminology:The side opposite the right angle is called the hypotenuse...
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
developers.
While JScript .NET can be used to create Windows Forms applications, JScript .NET will have some trouble, as delegates can only be consumed in JScript .NET and not created. Thus, custom events are hard to emulate in JScript .NET.
In many programming languages, the main function is where a program starts execution. It is responsible for the high-level organization of the program's functionality, and typically has access to the command arguments given to the program when it was executed....
function.
JScript .NET does not require explicit type declaration on variables. (In C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, the use of templates and generics can be compared to this, loosely emulated with template specialization etc.)
JScript .NET also does not require explicit type casts
Type conversion
In computer science, type conversion, typecasting, and coercion are different ways of, implicitly or explicitly, changing an entity of one data type into another. This is done to take advantage of certain features of type hierarchies or type representations...
on variable use in the program. Code used to retrieve a string of characters, but only used for integer numbers can be cast implicitly; the vice-versa can be done without error at compile time, but there is a chance of loss of precision or data.
e.g.:
import System;
Console.WriteLine("Hello, what's your name?");
Console.WriteLine("Type your name: ");
var _name = Console.ReadLine;
Console.WriteLine("Hello, " + _name);
Differences with Java
JScript .NET syntax and lexical conventions are similar to Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
. JScript was originally Microsoft's implementation of ECMAScript
ECMAScript
ECMAScript is the scripting language standardized by Ecma International in the ECMA-262 specification and ISO/IEC 16262. The language is widely used for client-side scripting on the web, in the form of several well-known dialects such as JavaScript, JScript, and ActionScript.- History :JavaScript...
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
, though it is unrelated to Java. Thus, users of Java and other C-derived languages will find JScript easier to learn.
JScript .NET allows developers to use untyped variables, and can sometimes infer their type from their usage to optimize the compiled code. On the other hand, Java requires all variables to be typed.
JScript .NET can add properties and methods to objects in run-time, while Java objects always conform to their declared interface.
JScript .NET supports global variables, something Java does not.
Differences with older versions of JScript
JScript .NET allows developers to declare variables and functions with type information (e.g., var x : String;), while type information for JScript's variables and functions cannot be declared (e.g., var x;).
JScript .NET scripts are not interpreted, but executed independently. When executed, a JScript .NET application will invoke the CLR
Common Language Runtime
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
Common Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
instructions without using an interpreter.
JScript .NET can be run without the presence of a browser or another scripting engine
Scripting language
A scripting language, script language, or extension language is a programming language that allows control of one or more applications. "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the...
as the compiler can generate standalone executable
Executable
In computing, an executable file causes a computer "to perform indicated tasks according to encoded instructions," as opposed to a data file that must be parsed by a program to be meaningful. These instructions are traditionally machine code instructions for a physical CPU...
s and assemblies. However these still require .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
to be installed in order to run.
JScript .NET provides access to the .NET Framework BCL (Base Class Library
Base Class Library
The Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...
), providing much more functionality.
JScript .NET is only available as a scripting language for ASP.NET
ASP.NET
ASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages ...
, the technology used to generate web pages; thus, JScript .NET takes a similar role to PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
and other server-side scripting languages. Internet Explorer, however, is still using only the older JScript engine, so JScript.NET cannot be used to script web pages (or HTAs or HTCs). In this regard, JScript is much more versatile than JScript .NET.
JScript is a scripting language based on the ECMAScript standard that is used in Microsoft's Internet Explorer.JScript is implemented as a Windows Script engine. This means that it can be "plugged in" to any application that supports Windows Script, such as Internet Explorer, Active Server Pages,...
ActionScript is an object-oriented language originally developed by Macromedia Inc. . It is a dialect of ECMAScript , and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of...
The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.
