Novice understands the relationship between HTML, CSS, and JavaScript

Http://www.cnblogs.com/dreamingbaobei/p/5062901.html

Work for many years, has been busy with the application of various technologies, and now do not rush, ask what they are doing, what will not answer up, in retrospect work is often asked M.F.B. s to achieve a goal, with degrees Niang solve problems, but no time to understand the reasons, today from the perspective of the macro to summarize.
The most accurate way to design a Web page is to divide the page into three layers: the structure layer (HTML), the presentation layer (CSS), the Behavior layer (JAVASCRIPT).
First, HTML, CSS, JavaScript Introduction and simple division of labor

1. What is HTML (Hypertext Markup Language Hyper Text Markup Language), HTML is a language used to describe a Web page.
2, CSS (cascading style sheet Cascading style sheets), style defines how to display HTML elements, syntax is: selector {Property:value} (Selector { Property: Value})
3. JavaScript is a scripting language whose source code is not compiled until it is sent to the client, but instead sends a text-formatted character code to the browser to be interpreted by the browser to run

For a Web page, HTML defines the structure of the page, CSS describes the Web page, JavaScript settings A very classic example is that HTML is like a person's bones, organs, and CSS is human skin, with these two also constitute a vegetable, With JavaScript, this vegetable can react to stimuli, think, exercise, and give yourself cosmetic (change CSS) and so on, to become a living person.

If HTML is physical, CSS is appearances, JavaScript is the soul. No javascript,html+css is a vegetable, no JavaScript, CSS is a disfigured vegetable.
If the HTML is an architect, CSS is a dry decoration, JavaScript is a magician.

How to connect these three, of course, through the physical html,html of the Web page is always descriptive language, it is to the browser to describe their own, then how does it usually describe the specific page?

<! DOCTYPE HTML Public"-//W3C//DTD XHTML 1.0 transitional//en" "HTTP://WWW.W3.ORG/TR/XHTML1/DTD/XHTML1-TRANSITIONAL.DTD">"http://www.w3.org/1999/xhtml">"Content-type"Content="text/html; Charset=utf-8"/><title> Page Title </title><link rel="stylesheet"Type="Text/css"href="Mycss.css"/><script type="Text/javascript"Src="Myjs.js"></script>
This is one of the simplest HTML documents, the document says, browser Ah, I am following the standard XHTML1.0 Transition version specification (file type declaration), the encoding I used isUtf-8, my title is "page title", the style sheet describing my appearance is the mycss.css file of my same directory, the JavaScript code related to me in my sibling myks.js file, my content has a paragraph, the content of the paragraph is "This is a paragraph".

Second, HTML, CSS, JavaScript development
1, the version of HTML
Hypertext Markup Language (first edition)-published as a working group on Internet Engineering (IETF) in June 1993 (not a standard):
HTML 2.0--released in November 1995 as RFC 1866, declared obsolete after RFC 2854 was released in June 2000
HTML 3.2--January 14, 1997, the recommended standard
HTML 5
HTML 5
HTML 4.0--December 18, 1997, the recommended standard
HTML 4.01 (minor improvements)--December 24, 1999, the recommended standard
HTML 5--October 28, 2014, the recommended standard [4]

Now we're only talking about HTML 4.01 and HTML5, because the 2000 World Wide Web Consortium announced the release of XHTML version 1.0. XHTML 1.0 is a new language optimized and improved on the basis of HTML 4.0, designed to be based on XML applications. While XHTML is almost identical to HTML 4.01, HTML has become more rigorous, more flexible, and more integrated with CSS from the initial development to XHTML. In principle, most of the pages you can see now are in the two versions of HTML4 or HTML5.
HTML5
It is a major modification of the HTML5, although the HTML5 standard is still in development, but can not hinder its unstoppable pace, do not HTML5 you out, we often for HTML5 and HTML5, in fact, for the lower end of the front (I do), especially with div+ CSS implementation of the Web page, really change little.
So, where is the essence of HTML5? This has to be said separately, see "HTML5 's introduction and in-depth understanding"

2. Version of CSS (level)
1996, the CSS1 officially launched;
1998, the CSS2 officially launched;
CSS2.1 is now being recommended for use by the consortium;
CSS3 is now in development.
If the development of HTML is a continuous modification of the process, then the development of CSS is a continuous process, so in the use of CSS, do not need to use the same standard as the HTML line, the higher version of the browser to recognize the high version of the CSS definition, the lower version of the browser skip the knowledge of the CSS definition. Regardless of the version, the syntax of the CSS is simple, the selector: {attribute: Property value}, so the hot CSS3 does not extend the selector and attributes.
CSS3 new selectors and properties see "CSS3 new selector and properties"

3, JavaScript's past life
JavaScript is a literal-translation scripting language, and its interpreter is called the JavaScript engine, which is part of the browser, that is, JavaScript is interpreted by the client's browser, so before we talk about JavaScript's history, we need to talk about the browser. The first web browser was created in 1991 and later renamed Nexus, and then a variety of browsers appeared, until 1994, WorldWideWeb Netscape (Netscape) released the Navigator browser version 0.9, which is the first relatively mature web browser in history, followed by the 1995 Microsoft launched the Internet Explorer, from the browser war, Microsoft took the operating system bundled IE browser, Eventually won the overwhelming victory, the defeat of the war Netscape was later acquired, merged, dissolved. After a period of time, ie alone lead, after being opera,safari,firefox,chrome to carve out some market share, changed a single big situation.

But when it comes to JavaScript's history, it's important to mention a company and a person, Netscape company and its employees Brendan Eich, Netscape, after releasing navigator, is eager to solve the problem of browser interaction with users, JavaScript's father Brendan Eich only 10 days to invent livescript (let my generation sentiment), because Netscape high-level is a fan of Java, or to embrace the stir of Java's thighs, Livascript renamed to Javascript,brendan eich his ideas are:
(1) Learn the basic grammar of C language;
(2) Learn the Java language data type and memory management;
(3) using the scheme language to promote the function to the status of "first Class citizen";
(4) Using the Self language, use the inheritance mechanism based on prototype (prototype).
So, theJavaScript language is actually a mixture of two language styles----(Simplified) functional programming + (Simplified) object-oriented programming.
JavaScript 1.0 was a huge success, and Netscape later launched 1.1, and then Microsoft, as a competitor, added a JavaScript implementation called JSCRIPT (which differs in order to avoid infringement) in its own IE3. The normalization of JavaScript was put on the agenda, and in 1997 the proposal to JavaScript1.1 was presented to the European Association of Computer Manufacturers (ECMA), where the ECMA led a few months of efforts to complete the ecma-262--definition of a ECMAScript the standard of the new scripting language.
While JavaScript and ECMAScript are often used to express the same meaning, JavaScript has much more to say than ECMA-262.
A complete JavaScript implementation should consist of three parts:
(1) core (ECMAScript), which describes the syntax and basic objects of the language.
(2) Document Object Model (DOM), which describes methods and interfaces for handling Web page content.
(3) A Browser object model (BOM) that describes the methods and interfaces that interact with the browser.
1995 invented the javascript,1997 year on the introduction of international standards, the urgent need for browser and user interaction, JavaScript development is too fast, javascript specifications have not come and adjusted, it cured. By contrast, international standards were enacted almost 20 years after the advent of the C language.
JavaScript has a lot of flaws, but JavaScript has no place in front of you,
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Links: http://www.zhihu.com/question/29898305/answer/45987802
Source: Know
Novice understands the relationship between HTML, CSS, and JavaScript