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This article mainly introduces "what on earth is javascript". In daily operation, I believe many people have doubts about what javascript is. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "what is javascript in the end?" Next, please follow the editor to study!

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

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

JavaScript is a Web-oriented programming language, which is supported by all web browsers. It is one of the most widely used scripting languages at present, and it is also a basic tool that must be mastered in web design and Web applications. It has been widely used in Web application development, which is often used to add a variety of dynamic functions to web pages and provide users with a more smooth and beautiful browsing effect.

History of JavaScript

In February 1995, Netscape released Netscape Navigator 2 browser and provided a free development tool-LiveScript. Because Java was popular at that time, Netscape renamed LiveScript to JavaScript, which was also the original version of JavaScript 1.0.

Because of the popularity of JavaScript 1.0, Netscape released JavaScript 1.1 in Netscape Navigator 3. Soon after, Microsoft added scripting capabilities to Internet Explorer 3. In order to avoid disputes with Netscape's JavaScript, Microsoft specifically named it JScript.

In 1997, the European Association of computer Manufacturers (ECMA) developed a scripting language standard, ECMA-262, based on JavaScript 1.1, and named it ECMAScript.

In 1998, the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC) adopted the ECMAScript standard (ISO/IEC-16262). Since then, browser manufacturers have adopted ECMAScript as the standard for their JavaScript implementation. JavaScript has officially moved from going its own way to standardizing and unifying.

JavaScript composition

ECMAScript is the standard of JavaScript, but it is not the same as JavaScript, nor is it the only specification that has been standardized.

In fact, a complete JavaScript implementation consists of three different parts:

ECMAScript: the core of the language.

Document object Model (Document Object Model,DOM): Web document operation standard.

Browser object Model (BOM): the basis for client and browser window operations.

Web browsers are just one of the hosting environments for ECMAScript implementations. The hosting environment provides not only the basic ECMAScript implementation, but also a variety of extended functions.

The document object model is the application programming interface (API) of HTML. DOM maps the entire document to a tree node structure to facilitate quick access and manipulation by JavaScript scripts.

IE3.0 and Netscape Navigator 3.0 provide a new feature, BOM (browser object Model). Using BOM, you can access and manipulate browser windows, such as moving windows, access history, dynamic navigation and so on. Unlike DOM, BOM is only a part of JavaScript and does not form a normative standard, but all browsers support it by default.

The JavaScript scripting language has the following characteristics:

Scripting language. JavaScript is an interpreted scripting language. Languages such as C and C++ are compiled and then executed, while JavaScript is explained line by line in the process of running the program.

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

simple. The JavaScript language uses weak variable types and does not make strict requirements on the data types used. It is a scripting language based on Java basic statements and control, and its design is simple and compact.

Dynamic. JavaScript is an event-driven scripting language that responds to user input without going through a Web server. When visiting a web page, JavaScript can directly respond to these events when the mouse clicks or moves up and down, window movement and other operations in the web page.

Cross-platform. The JavaScript scripting language does not depend on the operating system and only needs the support of browsers. So a JavaScript script can be written and used on any machine, as long as the browser on the machine supports the JavaScript scripting language, and JavaScript is already supported by most browsers. Unlike server-side scripting languages, such as PHP and ASP,JavaScript, are mainly run on users' browsers as client-side scripting languages and do not require server support. So in the early days, programmers preferred JavaScript to reduce the burden on the server, while at the same time brought another problem, security.

At this point, the study of "what exactly is javascript" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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