What is the difference between jscript and javascript

Difference: JScript is an active scripting language developed by Microsoft; JavaScript is an interpreted scripting language developed by Netscape. JavaScript is for all browsers, Jscript is only for Microsoft's IE browser.

The operating environment of this tutorial: windows7 system, javascript1.8.5&&JScript version 8.0, Dell G3 computer.

JScript introduction

JScript is an active scripting language developed by Microsoft and is Microsoft's implementation of the ECMAScript specification. JScript was originally released with Internet Explorer 3.0 in August 1996. When web programmers talk about JavaScript in Internet Explorer, they actually mean JScript.

Like other active scripts, it was later supported by Windows Script Host (WSH) and Active Server Pages. A typical JScript source file uses the .js extension.

The latest version of JScript is JScript .NET based on the yet-to-be-finalized ECMAScript 4.0 version specification, and can be compiled in Microsoft's .Net environment. JScript adds many features to the ECMA specification.

Functions of Jscript:

1. JScript 8.0 is a new generation version of Microsoft’s implementation of the ECMA 262 language. By combining the feature set of previous versions of JScript with the best features of class-based languages, JScript 8.0 contains the best of both worlds. Improvements in JScript 8.0 (being developed in conjunction with ECMAScript version 4) include: true compiled code, typed and untyped variables, late and early binding, classes with inheritance, function overloading, property accessors, and more ), packages, cross-language support, and full access to the .NET Framework.

2. JScript 8.0 is a true object-oriented scripting language. Although JScript 8.0 can use classes, types, and other high-level language features to write reliable applications, it still retains its "scripting" character, supporting typeless programming, expando functions and classes, dynamic code execution (using eval), and more.

3. JScript 8.0 is not only an untyped language, but can also be used as a strongly typed language. In previous versions, JScript's loosely typed structure meant that variables took on the type of the value assigned to them. In fact, in previous versions users could not declare the data type of variables. JScript 8.0 allows type annotations for variables, which provides greater flexibility than previous versions of JScript. This method binds a variable to a specific data type so that the variable can only store data of that type.

In programming languages, strong typing has many advantages. In addition to the benefits gained when the data type used is just right for the data being used, there are several other benefits:

• Increased execution speed

• Runtime/compile-time type checking

• Self-documenting code

Finally, JScript 8.0 is not a simple version of another programming language , nor is it a simplification of anything. It is a modern scripting language that is widely used.

Introduction to JavaScript

JavaScript ("JS" for short) is a lightweight, interpreted or just-in-time compilation with function priority high-level programming language. Although it is famous as a scripting language for developing Web pages, it is also used in many non-browser environments. JavaScript is based on prototype programming, a multi-paradigm dynamic scripting language, and supports object-oriented, imperative and declarative ( such as functional programming) style.

JavaScript was first designed and implemented in 1995 by Brendan Eich of Netscape Company on the Netscape Navigator browser. Because Netscape was working with Sun, Netscape management wanted it to look like Java, hence the name JavaScript. But in fact its grammatical style is closer to Self and Scheme.

JavaScript script language has the following characteristics:

(1) Script language. JavaScript is an interpreted scripting language. Languages ​​such as C and C are compiled first and then executed, while JavaScript is interpreted line by line during the running of the program.

(2) Based on objects. JavaScript is an object-based scripting language that can not only create objects but also use existing objects.

(3)Simple. The JavaScript language uses weakly typed variable types and does not impose strict requirements on the data types used. It is a scripting language based on Java's basic statements and controls, and its design is simple and compact.

(4)Dynamic. JavaScript is an event-driven scripting language that can respond to user input without going through a Web server. When visiting a web page, JavaScript can directly respond to these events when the mouse is clicked, moved up or down, or moved in the window.

(5) Cross-platform. JavaScript scripting language does not depend on the operating system and only requires browser support. Therefore, after writing a JavaScript script, it can be brought to any machine for use, provided that the browser on the machine supports the JavaScript scripting language, and JavaScript has been supported by most browsers. [5]

Unlike server-side scripting languages, such as PHP and ASP, JavaScript is mainly used as a client-side scripting language to run on the user's browser and does not require server support. Therefore, in the early days, programmers preferred JavaScript to reduce the burden on the server, but at the same time it also brought about another problem: security.

As servers become more powerful, although programmers prefer scripts running on the server to ensure security, JavaScript is still popular for its cross-platform and easy-to-use advantages. At the same time, some special functions (such as AJAX) must rely on Javascript to be supported on the client side. With the development of engines such as V8 and frameworks such as Node.js, and their features such as event-driven and asynchronous IO, JavaScript is gradually used to write server-side programs.

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