1.Javascript Introduction:
Born in 1995, Netscape invented, then gradually become a browser essential feature, its purpose is no longer limited to simple form verification, but with the browser window and interactive almost all the functions. Today's JavaScript has become a comprehensive programming language that can handle complex computations and interactions, and it has the features of closures, anonymous functions, and even metaprogramming.
It is a simple and complex language, it takes only a few hours to learn to use it, and it's complicated because it takes years to really master it. To really grasp the need to understand its history, nature, and limitations.
History:
It is a scripting language called LiveScript, published in February 1995 by Brendan Eich, a member of Netscape, that can be used in browsers and servers, and the name on the server is called Livewire, In order to complete the development of LiveScript before the release date, Netscape and sun set up a development alliance. When the release of the media to catch up with the real hot Java car, conveniently renamed JavaScript.
1.0 was a great success, and later a 1.1 version was released in Netscape Navigator3. Microsoft's entry into Web browsers in the August 1996 was indeed a major step, and although it was a disgrace to Netscape, it also marked a big step forward for JavaScript as a language.
Microsoft has pushed the standardization of JavaScript onto the agenda, and several vendors didn't have the syntax and features of standard JavaScript. The 1997 Javascript1.1 proposal was submitted to the European Computer Manufacturers Association (ECMA), which later completed ecma262--a new scripting language standard named ECMAScript. The second year internationalization Standards organization and the International Electrotechnical Commission also adopted the ECMAScript as the standard, from now on the browser's developers are committed to making ECMAScript as the basis for JavaScript implementation, to varying degrees achieved success.
Realize:
Core (ECMAscript)
Document Object Model (DOM)
Browser object Model (BOM)
The Document Object Model (DOM) is for XML but is extended to the HTML Application Programming interface (API), and the DOM maps the entire page to a hierarchical node structure, and each component of the HTML page is a type of node that contains different types of data.
The tree diagram of documents created by the DOM allows developers to take the initiative to control the content and structure of the page, with the help of the DOM developers who can easily delete, add, replace, and modify any node.
To avoid the compatibility of Netscape and Microsoft in the DOM technology, the World Wide Web Consortium, which is responsible for the standards of web-based Communications, began planning the DOM.DOM1 1998 as the recommended standard for the consortium, which has two modules that make up the DOM core and Dom Html,dom's core plan is how to map an xml-based document structure, and DOM html is his extension.
DOM2 on the basis of DOM1 and extended the mouse and user events, scope, traversal and operation of the document tree interface, such as thin modules. And through the object interface to increase the support of CSS. DOM3 further expands the DOM to add a unified way to load and save documents. Added DOM validation and started supporting the XML 1.0 specification.
Then the browser tries to start supporting DOM1, and gradually to fully support DOM3.
The browser object model (BOM) uses a BOM to control the part of the browser display page, the BOM as a JavaScript implementation has been no relevant standards, until the HTML5 to completely solve the problem. Essentially, the BOM handles only browser windows and frames, but it's customary to count all extensions for JavaScript as part of the BOM. The following are some extensions:
pop-up browser window function;
Move zoom, close browser window;
A Navigator object that provides browser detail information;
Location object in which the browser loads page details;
Screen object for display resolution details;
Support for cookies;
XMLHttpRequest and IE are activxobject objects.
JavaScript provides core language functionality by ECMAScript, DOM provides methods and interfaces for manipulating Web content, and BOM provides a way to interact with browsers; These three components are in the current browser ie, Firefox, Chrome, Safari and opera have received varying degrees of support, ECMASCRIPT5 support is getting higher, but DOM support is a big difference.
