JavaScript Advanced Programming Chapter--javascript Introduction

JavaScript Advanced Programming Chapter--javascript Introduction
The original purpose of the JavaScript developed by Netscape is to handle some of the input validation operations that the server is responsible for, and before JS comes out, it must be
Send form data to a server-side user to get feedback. Today's JS is no longer limited to simple data validation, and has a browser window
interface and its content, JS has developed into a full-featured client-facing programming language.
JavaScript was developed by Netscape Inc., formerly known as LiveScript, to cater to the Java heat of the time, so renamed JavaScript, so
JavaScript is not java!!. But at the same time, Microsoft has developed JScript, because there is no standard specification JS syntax and features, that is, in the present
Two different versions, Netscape JavaScript in navigator and JScript in IE, and later ECMA prescribes the syntax and features of JS,
Define ECMAScript as the standard for the new scripting language
In short, JavaScript is a scripting language specifically designed for Web page interaction a complete JavaScript consists of three parts:
Core (ECMAScript) Document Object Model (DOM) Browser object Model (BOM)

Core (ECMAScript): Provides core language functionality. ECMAScript specifies a part of the JavaScript language:
syntax, type, statement, keyword, reserved word, operator, object. is a description of all aspects of the implementation of the standard provisions,
ECMAScript has more than one version, no update, the fifth edition was officially released on December 3, 2009. ECMAScript compatible: to be
ECMAScript, the implementation must do the following: 1. Supports all types, values, objects, properties, functions described by ECMA-262
and the syntax and semantics of the program "2. Support for Unicode Standard 3. Add" more types, values, objects, properties ECMA-262 not defined "
and functions, which are the new properties of new objects and objects that are not specified in the standard 4. You can modify and extend the built-in regular expression syntax
Today's five major web browsers are all compatible with ECMAScript.

Document Object Model (DOM): Provides methods and interfaces for accessing and manipulating Web page content, and the DOM is for HTML and XML documents
The API (Application Programming Interface) Dom depicts a hierarchical tree of nodes that allows developers to add, remove, and modify nodes of a page.
These nodes also contain different types of data. Dom level, the DOM1 level is mainly the structure of the mapping document, the DOM2 level has new views,
Events, styles, traversal, and scopes, the DOM3 scale further expands the DOM, introducing a way to load and save documents in a uniform way, adding
The method of validating the document, as well as extending the DOM core.

Browser object Model (BOM): Provides methods and interfaces for interacting with the browser, essentially the BOM only handles browser windows and frames,
But it is also customary to count all browser-specific JavaScript extensions as part of the BOM, including some of the following extensions: 1. Pop up a new browser
The function of the window 2. The ability to move, zoom, and close the browser window 3. Navigator object that provides browser details 4. Provide
Location Object 5 For detailed information about the page loaded by the browser. Screen Object 5 that provides detailed information about the user's display resolution. Right
Support for Cookies 6. ActiveXObject Custom objects like XMLHttpRequest and ie.

The three parts of JavaScript are compatible and supported in a variety of ways, in the current 5 mainstream browsers.

JavaScript Advanced Programming Chapter--javascript Introduction