Basic front-end knowledge

Basic front-end knowledge

1,Front end: Develop computer software on the client through a browser

2,URL(Same Resource Locator): A Concise representation of the location and access method of resources that can be obtained from the Internet. It is the address of standard resources on the Internet. Each file on the Internet has a unique URL. It contains information that specifies the location of the file and how the browser should handle it.

3,HTTP protocol(Hypertext Transfer Protocol): a data transfer protocol that defines the rules for communication between browsers and web servers over the Internet. It not only ensures that the computer transfers hypertext documents correctly and quickly, but also determines which part of the transmitted documents and which part of the content is first displayed (such as text before graphics.

HTTP is an application layer protocol consisting of requests and responses. It is a standard client server model. HTTP is a stateless protocol. Stateless means that the Protocol has no memory for transaction processing, the lack of status means that if subsequent processing requires the previous information, it must be re-transmitted, which may increase the amount of data transmitted each connection.

When the client sends a request to the web service, we call it an HTTP request sent by the client,HTTP RequestIt is divided into four parts:Request Line,Request Header,A blank lineAndMessage Body.

The request line, such as GET/image/logo.gif HTTP/1.1

Indicates that the http method is GET, and the request URL is image/logo.gif(from the imagedirectory to request the logo.gif file). The http Version is HTTP/1.1.

When the web server returns a response to the client, we call it a response from the server.HTTP ResponseThe HTTP response is divided into four parts:Status line,Response Header,A blank lineAndMessage Body.

The status line format is HTTP_version space Status_code space Reason_Phrase.

HTTP_version indicates the http Version. Status_code indicates the response code, which is represented by three numbers. Reason_Phrase indicates the response description.

4,UTF-8(8-bit Unicode Transformation Format): a variable-length character encoding for Unicode, also known as Wanguo code. Ken-Thompson was created in July 1992. The UTF-8 is 1 to 6 bytes encoded unicode characters, used on the web page can display the Chinese Simplified, traditional and other languages (such as English, Japanese, Korean, etc.) on the same page ).

5,Differences between HTML and XHTML

HTML (Hyper Text Markup Language): hypertext Markup Language. It is a basic web page design language that uses tag to describe web pages.

XHTML (Extensible HyperText Markup Language): Extensible HyperText Markup Language. The goal is to replace HTML. XHTML is a more rigorous and pure HTML version, which is a W3C standard and is redefined as an XML application.

Some rules in XHTML, such as element names and attribute names, cannot be capitalized, attribute values are enclosed in quotation marks, attributes cannot be abbreviated, And the id attribute is used instead of the name attribute, all tags must have an ending mark, all tags must be reasonably nested, the image must have a text description, and "--" is not used in comments.

6,XML: Extensible markup language, a subset of the standard General Markup Language (SGML), suitable for web transmission.

XML requires that all tags appear in pairs and are case sensitive.

The difference between XML and HTML is that the core of XML is data, and its focus is on data content. HTML is designed to display data, with the focus on data display.

What is the basic knowledge required by the front-end of Xiaobai learning?

The fastest way to do this is to learn to use the various front-end frameworks of the current process, such as bootstrap. In addition, jquery must be able to learn the basic knowledge of html5 and css3. Others are accumulated experience.

I have learned basic java knowledge and want to know how to develop web Front-end services.

Then you can start to look at html, jsp, js, css and other related technologies. These are front-end web technologies.