Microsoft-тың JScript NET бағдарламалау тілі

Programming language developed by Microsoft

JScript NET is a NET programming language developed by Microsoft. The primary differences between JScript and JScript NET can be summarized as follows:

Firstly, JScript is a scripting language, and as such programs (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 (CLR) for execution, which requires that the code be compiled to Common Intermediate Language (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/COM technologies, and relies primarily on ActiveX components to provide much of its functionality (including database access via ADO, file handling, etc. ), whereas JScript NET uses the NET Framework 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 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 supports JScript NET.

The following are prime examples of language differences between JScript NET and other NET languages, including comparisons.

JScript NET does not require a main function that the operating system must call directly when executing a JScript NET application, as such, JScript NET program flow can be based 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 of an angle for a right triangle). JScript NET is closely linked to C syntax, and is thus very easy to learn for C#, Java or C++ 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.

JScript NET syntax and lexical conventions are similar to Java in that both are derived from C. JScript was originally Microsoft's implementation of ECMAScript, which is more commonly known as JavaScript, 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.

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 can not 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. The CLR will execute the CIL instructions without using an interpreter. JScript NET can be run without the presence of a browser or another scripting engine as the compiler can generate standalone executables and assemblies. However these still require NET Framework to be installed in order to run. JScript NET provides access to the NET Framework BCL (Base Class Library), providing much more functionality. JScript NET is only available as a scripting language for ASP. NET, the technology used to generate web pages; thus, JScript NET takes a similar role to PHP 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.