Introduction to basic concepts and technologies used in Web development_HTML/Xhtml_Web page production

Today, this article introduces some basic concepts and technologies used in web development to beginners. There are 26 items in total from A to Z, each corresponding to a concept or technology.

A — AJAX

AJAX stands for "Asynchronous JavaScript and XML" (Asynchronous JavaScript and XML), which is a web development technology for creating interactive web applications. According to Ajax creator Jesse James Garrett, AJAX:

Use XHTML CSS to represent information;
Use JavaScript to operate DOM (Document Object Model) for dynamic display and interaction;
Use XML and XSLT for data exchange and related operations;
Use XMLHttpRequest object to interact with the Web The server does asynchronous data exchange;
uses JavaScript to tie everything together.
Similar to DHTML or LAMP, AJAX does not refer to a single technology, but organically utilizes a series of related technologies. In fact, some "derivative/composite" technologies based on AJAX are emerging, such as AFLAX.

B — Browser

A web browser is a software that displays files in a web server or file system and allows users to interact with these files. It is used to display text, images and other information on the World Wide Web or LAN, etc. These texts or images can be hyperlinks to other websites, allowing users to browse various information quickly and easily. Most web pages are in HTML format, and some web pages require specific browsers to display correctly. The common web browsers on personal computers, in order of market share in January 2010, are Microsoft's Internet Explorer, Mozilla's Firefox, Google's Google Chrome, Apple's Safari and Opera Software's Opera. Browsers are the most commonly used client programs. Web developers should ensure that their programs work properly across all major browsers.

C — CSS

Cascading Style Sheets, also known as: Cascading Style Sheets, English: Cascading Style Sheets, abbreviated as CSS, a standard defined and maintained by W3C, a method used to add styles to structured documents (such as HTML documents or XML applications) (fonts, spacing, colors, etc.) computer language. The latest version is CSS 2.1, which is a candidate recommendation standard of W3C. The next version, CSS 3, is still under development.

D — DOM

Document Object Model (DOM) is a standard programming interface recommended by the W3C organization for processing extensible markup languages. The history of the Document Object Model can be traced back to the "browser wars" between Microsoft and Netscape in the late 1990s. In order to compete for life and death between JavaScript and JScript, both parties gave browsers powerful functions on a large scale. Microsoft has added many proprietary things to web technology, including VBScript, ActiveX, and Microsoft's own D HTML format, which makes many web pages unable to display properly using non-Microsoft platforms and browsers. DOM is the masterpiece brewed at that time.

E — Events

Events are operations that can be recognized by the control, such as pressing the OK button, selecting a radio button or check box. Each control has its own identifiable events, such as form loading, click, double-click and other events, text changes in edit boxes (text boxes), etc. Modern web applications rely heavily on event-driven .

Events include system events and user events. System events are triggered by the system, such as every 24 hours, the deposit date of a bank depositor is increased by one day. User events are triggered by the user, such as the user clicking a button to display specific text in a text box. Event-driven controls perform a certain function. The object that triggers the event is called the event sender; the object that receives the event is called the event receiver.

Using the event mechanism, it can be realized: when a certain state of the class object changes, the system will call the method in the class to handle this event through some way, or the object that triggers the control event will call all the existing methods of the control. Registered event handlers, etc.

F — Firebug

Firebug is an extension of the web browser Mozilla Firefox and is a debugging tool. Users can use it to debug, edit, and even delete the CSS, HTML, DOM, and JavaScript code of any website. Firebug also provides other web development tools, such as Yahoo!'s web page speed optimization suggestion tool YSlow. Firebug was written by Joe Hewitt. He is one of the original founders of Firefox.

G — Grid

Grid, also called grid, but by definition, grid is more accurate. Find a more appropriate definition of web page grid system on the Internet: a regular grid array is used to guide and standardize the layout and information distribution of web pages. The web grid system is developed from the flat grid system. For web design, the use of the grid system can not only make the information presentation on the web page more beautiful and easy to read, but also more usable. Moreover, for front-end development, web pages will be more flexible and standardized. If there are many CSS frameworks that support grid functions, you can refer to the article "Introducing 27 Classic CSS Frameworks".

H — HTML

Hypertext Markup Language (English: HyperText Markup Language, HTML) is a markup language designed for "web page creation and other information that can be seen in a web browser". HTML is used to structure information - such as headings, paragraphs, lists, etc., and can also be used to describe the appearance and semantics of a document to a certain extent. HTML, originally defined by Tim Berners-Lee and further developed by the IETF using a simplified SGML (Standard General Markup Language) syntax, later became an international standard maintained by the World Wide Web Consortium (W3C).

The latest version is HTML5 which is the next major revision of HTML and is still in the development stage. The goal is to replace the HTML 4.01 and XHTML 1.0 standards established in 1999, in order to make network standards meet contemporary network needs when Internet applications are developing rapidly. When talking about HTML5 in a broad sense, it actually refers to a set of technology combinations including HTML, CSS and JavaScript.

I — IE

Windows Internet Explorer (formerly known as Microsoft Internet Explorer, abbreviated as Internet Explorer, abbreviated as IE) is a web browser launched by Microsoft. As of September 2010, statistical data shows that Internet Explorer's market share is as high as 59.65%. Although it is still the most widely used web browser, its market share differs by more than 30% from its peak in 2003.

Internet Explorer supports some standardized technologies to a certain extent, but there are also many operational gaps and compatibility failures, which has led to increasing criticism from technology developers. The increase in criticism is largely due to the fact that Internet Explorer's competitors have provided relatively complete technical support and that Standards-compliant applications are becoming more widely used. Because Internet Explorer is widely used around the world, web developers seeking cross-platform code often find Internet Explorer's vulnerabilities, proprietary feature sets, and imperfect support for standards.

The Internet Explorer 9 browser released on March 14, 2011 has greatly improved its support for W3C specifications such as CSS3 and HTML5. This version is also the first version of the Internet Explorer browser to adopt GPU acceleration. The official version was tested in Acid3 It scored 95/100 points, which is a great improvement compared to previous versions. It can be considered that starting from Internet Explorer 9, the Internet Explorer browser's support for W3C specifications will no longer be a problem.

J — JavaScript

JavaScript is a scripting language widely used in client-side web development. It is often used to add dynamic functions to HTML web pages, such as responding to various user operations. Originally designed by Brendan Eich at Netscape, it is a dynamic, weakly typed, prototype-based language with built-in support classes. JavaScript is a registered trademark of Sun Microsystems. Ecma International developed the ECMAScript standard based on JavaScript. JavaScript can also be used in other situations, such as server-side programming. The complete JavaScript implementation contains three parts: ECMAScript, Document Object Model, and Byte Order Notation.

Netscape originally named its scripting language LiveScript and Netscape changed its name to JavaScript after cooperating with Sun. JavaScript was originally designed to be inspired by Java. One of the purposes is to "look like Java", so there are similarities in syntax, and some names and naming conventions are also borrowed from Java. But the main design principles of JavaScript are derived from Self and Scheme. The similarity in names between JavaScript and Java was the result of an agreement between Netscape and Sun for marketing considerations at that time. In order to gain a technical advantage, Microsoft launched JScript to compete with JavaScript's scripting language. For interoperability, Ecma International (formerly the European Computer Manufacturers Association) created the ECMA-262 standard (ECMAScript). Both are now implementations of ECMAScript. Although JavaScript is promoted and advertised as a scripting language for non-programmers rather than a programming language for programmers, JavaScript is very rich in features.

K — Keyword Optimization

Keyword optimization, also called Search Engine Optimization (SEO), is a way to use the search rules of search engines to improve the ranking of target websites in relevant search engines. Since many studies have found that search engine users tend to only pay attention to the first few entries in search results, many websites hope to influence the ranking of search engines in various ways. This is especially true for websites that rely on advertising to make a living.

The so-called "search engine optimization" refers to making the website more easily accepted by search engines. The search engine will compare some correlation data between the content of the websites, and then the browser will present the content to the searcher in the fastest and most complete way.

Search Engine Optimization For any website, if it wants to succeed in website promotion, Search Engine Optimization is a crucial task. At the same time, as search engines continue to change their ranking algorithm rules, each algorithm change will cause some well-ranked websites to lose their reputation overnight, and the direct consequence of losing rankings is the loss of the website's inherent considerable traffic. Therefore, every change in search engine algorithms will cause a lot of commotion and anxiety among websites. It can be said that search engine optimization is an increasingly complex task.

L — Less

Less was originally a ruby ​​gem that gave CSS dynamic language features, including variables, operators, and nested rules. In fact, the real function of Less is to convert CSS that uses advanced features into standard CSS. These are completed through the Http Handler when the web client initiates a request. It can also be done while editing. In addition, Less can be configured to automatically minimize the generated CSS files, which not only saves bandwidth, but also improves the end-user experience. There is also a .Net version of Less.

M —MVC

MVC pattern (Model-View-Controller) is a software architecture pattern in software engineering. It divides the software system into three basic parts: Model, View and Controller. The MVC pattern was first proposed by Trygve Reenskaug in 1974. It is a software design pattern invented by Xerox PARC in the 1980s for the programming language Smalltalk. The purpose of the MVC pattern is to implement a dynamic programming design, simplify subsequent modifications and expansions of the program, and make it possible to reuse certain parts of the program. In addition, this mode makes the program structure more intuitive by simplifying the complexity. The software system separates its basic parts and also gives each basic part its due functions.

N — Node.JS

Node is a Javascript runtime environment (runtime). In fact, it encapsulates the Google V8 engine (applied to the Google Chrome browser). The V8 engine executes Javascript very quickly and has very good performance. Node has optimized some special use cases and provided alternative APIs to make V8 run better in non-browser environments. For example, in a server environment, processing binary data is usually essential, but Javascript does not support this enough. Therefore, V8.Node adds the Buffer class to process binary data conveniently and efficiently. Therefore, Node not only simply uses V8, but also optimizes it to make it more powerful in various environments. Node.js does it all, but most importantly, it provides a way to run Javascript outside of a web browser. Javascript is widely used in front-end development of websites. Node enables this popular programming language to run in more environments, even the server side of a website.

O — Object

Object is a term in Object Oriented. It not only represents a specific thing in the objective world problem space (Namespace), but also represents a basic element in the software system solution space. In a software system, an object has a unique identifier. The object includes Properties and Methods. Properties are the information that needs to be remembered, and methods are the services that the object can provide. In Object Oriented software, an object is an instance of a class.

P — PHP

PHP (Hypertext P reprocessor) is a scripting language that runs on a computer. Its main purpose is to process dynamic web pages. It also includes a command line interface (command line interface) or generates a graphical user interface (GUI). program. PHP was first invented by Rasmus Lerdorf in 1995, and the standard of PHP is now maintained by the PHP Group and the open source community. PHP uses PHP License as the license agreement, but because this agreement restricts the use of the PHP name, it is incompatible with the open source license agreement GPL.

PHP has a wide range of applications, especially in the development of web programs. Generally speaking, PHP is mostly run on a web server, and the web pages browsed by users are generated by running PHP code. PHP can run on most servers and operating systems, and using PHP is completely free. According to April 2007 statistics, PHP has been installed on more than 20 million websites and 1 million servers.

Q — Query

Query has many meanings. For example, query languages ​​are used to interact with extended systems that store data. A good example is SQL used to operate relational databases. Another meaning is that a query string is used as part of the URL to transfer data in web applications. The format of the query string is generally in the form of key-value pairs.

R — Regular Expressions

Regular Expression (English: Regular Expression, regex or regexp, abbreviated as RE), also translated as regular expression, regular expression, in computer science, refers to a series of expressions that are used to describe or match a certain A single string of strings with syntax rules. In many text editors or other tools, regular expressions are often used to retrieve and/or replace text content that matches a certain pattern. Many programming languages ​​support string manipulation using regular expressions. For example, Perl has a powerful regular expression engine built into it. The concept of regular expressions was originally popularized by tool software in Unix (such as sed and grep).

S — Source Control

Source code management, also known as version control, is a software engineering technique that ensures that the same program files edited by different people are synchronized during the software development process. Software designers often use version control to track and maintain changes in source code, files, configuration files, etc., and provide procedures for controlling these changes. In the simplest case, a software designer can keep many different versions of a program himself and number them appropriately. This simple approach has been used in many large software projects. This is a method that can achieve the goal, but it is not efficient enough. In addition to having to maintain many almost identical program code backups at the same time; it also relies heavily on the self-cultivation and development discipline of software designers, but this is often the cause of errors.

Sometimes, it is necessary to have more than two versions of a program at the same time. For example: in a version for deployment, program errors have been corrected but no new features have been added; in another development version, there are new Features are being developed and new bugs need to be resolved, which requires different versions and modifications at the same time. In addition, in order to find "program errors" that only exist in a specific version, or to find out the version in which a "program error" occurs, software debuggers must also compare different versions of the program code to find the location of the problem.

T — TDD

Test-driven development is a modern computer software development method. Use testing to drive the design and implementation of software programs. Test driving became popular in the 1990s. Test-driven development is a program development method advocated in Extreme Programming. The method is mainly to write a test program first, and then code it to pass the test. The purpose of test-driven development is to get quick feedback and use an "illustrate the main line" approach to building a program.

A metaphor for test-driven development. Development can be viewed from two aspects: functionality and quality of implementation. Test-driven development is more like the development method of two hats thinking. First put on the function hat, with the help of testing, quickly implement the correct function; then put on the refactoring hat, under the protection of testing, by removing Redundant and duplicated code, improve code reusability, and achieve quality improvements. It can be seen that testing does belong to the core position in test-driven development and runs through the entire development.

U — Unit Testing

Unit testing (also called module testing) is a test for correctness testing of program modules (the smallest unit of software design). A program unit is the smallest testable component of an application. In procedural programming, a unit is a single program, function, process, etc.; for object-oriented programming, the smallest unit is a method, including methods in base classes (superclasses), abstract classes, or derived classes (subclasses).

Generally speaking, programmers will conduct at least one unit test every time they modify a program. During the process of writing a program, they are likely to conduct multiple unit tests to confirm that the program meets the requirements of the software specification (en: Specification) The goal of the work is to have no bugs; although unit testing is not necessary, it is not bad, and it involves project management policy decisions.

V — VIM

Vim is a text editor developed from vi. It is particularly rich in functions that facilitate programming, such as code completion, compilation, and error jumping, and is widely used among programmers. Tied with Emacs to become the most favorite editor for users of Unix-like systems. The first version of Vim was released by Bram Moolenaar in 1991. The initial abbreviation was V i IM iteration. As the functionality continued to increase, the official name was changed to V i IM proved. It is now released as free software under the open source code.

W — WordPress

WordPress is a blogging platform developed using PHP language. Users can set up their own blogs on servers that support PHP and MySQL databases. You can also use WordPress as a content management system (CMS). WordPress is a free open source project licensed under the GNU General Public License. The latest version is the official simplified Chinese version 3.0.5 released on February 24, 2011, and is available in multiple languages ​​including English.

X — XSS

Cross-site scripting (often referred to as XSS) is a security vulnerability attack on website applications that allows malicious users to inject code into web pages. Other users will affected. This type of attack usually involves HTML and user-side scripting languages.

Y — YUI

Yahoo! UI Library (YUI) is an open source JavaScript function library. In order to create a highly interactive web page, it uses coding technologies such as AJAX, DHTML and DOM. It also contains many CSS resources.

Z — Z index

Z-Index
is a CSS property that sets the stacking order of elements. Elements with a higher stacking order will always appear in front of elements with a lower stacking order. This property sets the position of a positioned element along the z-axis, which is defined as the axis extending vertically into the display area. If it is a positive number, it is closer to the user, and if it is a negative number, it is further away from the user.