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This article mainly introduces the relevant knowledge of "how to constitute javascript". The editor shows you the operation process through an actual case. The operation method is simple, fast and practical. I hope this article "how to constitute javascript" can help you solve the problem.

Javascript mainly consists of three parts: 1, ECMAScript, which describes the basic syntax and data types of the language; 2) document object Model (DOM), which is the application program interface between HTML and XML; 3. Browser object Model (BOM), which accesses and manipulates browser windows.

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

Although JavaScript and ECMAScript are usually used to express the same meaning, the meaning of JavaScript is much more than that specified in ECMA-262. A complete JavaScript implementation should consist of three parts:

Core (ECMAScript)

Document object Model (DOM)

Browser object Model (BOM)

1 、 ECMAScript:

The core of JavaScript, which describes the basic syntax of the language (var, for, if, array, etc.) and data types (numbers, strings, Boolean, functions, objects (obj, [], {}, null), undefined), ECMAScript is a set of standards that define what a language (such as JS) looks like.

2. Document object Model (DOM):

DOM (document object Model) is the application program interface (API) of HTML and XML. DOM will plan the entire page into a document at a node level. Each part of a HTML or XML page is a derivative of a node.

DOM represents documents by creating trees, giving developers unprecedented control over the content and structure of documents. Nodes (getElementById, childNodes, appendChild, innerHTML) can be easily deleted, added, and replaced with DOM API.

DOM level

DOM1

How DOM Core maps XML-based document structure

DOM html added objects and methods for html

DOM2

Expanded the mouse and user interface event, scope, traversal and other subdivision modules, through the object interface to increase the support for css.

The details are as follows:

DOM view: defines an interface to track different document views

DOM events: defines the interface for events and event handling

DOM style: defines css-based interfaces for manipulating element styles

DOM traversal and scope: a. Define the interface of traversing and manipulating document tree b. Added a method to validate documents

DOM3

Introduced the method of loading and saving documents in a unified way

3. Browser object Model (BOM):

The browser object Model (BOM) accesses and manipulates the browser window.

Action

Working with browser windows and frames

Js extension for browser operation

Specific function

The ability to pop up a new browser window

The ability to move, zoom and close browser windows

A navigator object that provides browser details

A location object that provides details of the page loaded by the browser

A screen object that provides details of the resolution of the user's display

Support for cookie

XMLHttpRequest-ActiveXObject

For example: pop up a new browser window, move, change and close the browser window, provide detailed web browser information (navigator object), detailed page information (location object), detailed user screen resolution information (screen object), support for cookies, and so on.

As a part of JavaScript, BOM does not have the support of related standards, and each browser has its own implementation. Although there are some unrealistic standards, it still brings some trouble to developers.

This is the end of the introduction to "how javascript is made up". Thank you for reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.

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