Shulou(Shulou.com)06/03 Report--

1. What is JavaScript?

JavaScript is a scripting language that belongs to the Internet. It is used by millions of web pages to improve design, validate forms, test browsers, create cookies and more, and it is the most popular scripting language on the Internet.

Why did 2.JavaScript show up?

Before JavaScript came out, form data had to be sent to the server to determine whether the user had not filled in a required field and entered an invalid value. However, at that time, the vast majority of Internet users used 28kbit/s "cats" (modems) to access the Internet, and frequently exchanging data with the server to complete simple form verification only increased the burden on the user-imagine the user filling out a form, clicking the submit button, and then waiting for 30 seconds. Finally, the server returned a message saying that a required field had not been completed. So Netscape, which was at the forefront of technological innovation at the time, decided to develop a client-side language to handle this simple validation. As a result, Brendan Eich, who works for Netscape, began to develop JavaScript, which was officially born in February 1995.

What is the relationship between 3.JavaScript and Java?

The JavaScript language has nothing to do with the Java programming language! Brendan Eich, the developer of JavaScript, began hoping to release a scripting language called LiveScript by February 1995-which will be used in both browsers and servers (it is called LiveWare on the server). Due to time constraints, Netscape formed a development alliance with Sun (the company that developed the Java programming language). On the eve of the official release of Netscape Navigator2, which supports the scripting language LiveScript, Netscape temporarily renamed LiveScript to JavaScript in order to take advantage of the media-hyped Java and make LiveScript sound like a famous family. Unfortunately, this choice makes it easy for people to confuse the two languages.

The realization of 4.JavaScript.

JavaScript is made up of three parts.

ECMAScript

DOM

BOM

ECMAScript: after the development of the JavaScript language, Netscape's competitor Microsoft decided to compete with Netscape Navigator's own product Internet Explorer3 browsing to include a JavaScript implementation called JScript (named JScript to avoid licensing issues related to JavaScript). Subsequently, there were problems with the two versions of JavaScript, and with the growing concern of the industry, the issue of JavaScript standardization was put on the agenda. In 1997, the proposal based on JavaScript1.1 was submitted to the European Association of computer Manufacturers (ECMA,European Computer Manufacturers Association), which appointed TC39 (Technical Committee No. 39) to complete ECMA-262-- 's standard for defining a new scripting language called ECMAScript. She has no dependency on Web browsers and defines the basics of the language, including syntax, types, statements, keywords, reserved words, operators, and objects. The latest version is the fifth edition of ECMA-262.

DOM: document object Model (DOM,Document Object Model). It is an application programming interface (API) for XML but extended for HTML. DOM maps the entire page to a multi-tier node structure. With the API provided by DOM, developers can easily delete, add, replace, or modify any node. At present, the latest one is DOM3. Note: the DOM0 level standard does not exist, it is only a reference point in the so-called DOM0 level knowledge history coordinates.

BOM: browser object Model (BOM,Browser Object Model). Developers can use BOM to control the part of the browser that is outside of the real page.

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