HTML

One 、Web Introduction to front end development

Web summary

Web origin

1984 Tim Berners Lee created the world's first World Wide Web navigation site, the world's first website

Web The characteristics and working principle of

1. Easy navigation and graphical interface
2. It's not about the platform
3. Distributed structure
4. dynamic
5. Interactivity

URL Introduce

URL Unified resource locator can be understood as a web address .
The composition is as follows ：
Protocol type ：// Server address （ Port number ）/ route / file name
Example ：
http://www.westos.org/bbs/index.html

Two 、HTML Web page structure

• HTML(Hyper Text Mark-up Language ) It's hypertext markup language , A language that describes the structure and presentation of a page document by using tag tags , Then the browser will parse it , And then show the results on the web page .

• Hypertext refers to hyperlinks
  A mark is a label

• 1).HTML The file is opened with an editor to display the text , It can be written Ben's way of editing .

• 2). HTML File open with browser , The browser will render the file as a web page according to the label description , The displayed page can be from a web page Links jump to another page .

HTML Basic structure

HTML The document type

The two types of documents commonly used at present are xhtml 1.0 and html5

HTML Document specification and annotation

xhtml The standard of document writing has been established ,html5 Can be partially complied with , You can also comply with all of them , Look at the development requirements .
1、 All labels have to be lowercase
2、 All attributes must be enclosed in double quotation marks
3、 All labels must be closed
4、img Must add alt attribute ( Description of the picture )

HTML notes

html Comments can be inserted into the document code , Comments are the explanation and explanation of the code , The content of the comment will not be displayed on the page ,html Insert comments into the code Approach is to ：

<!-- This is a comment -->

3、 ... and 、HTML label

Text label

Line wrap label

Tabs tab

div And span label

Picture label

Tag definition HTML Images on the page . There are two required properties ：src and alt.
attribute ：src: Picture name and url Address title： Text prompt properties
alt: Tips for image loading failure width/height： Image width / Height

Hyperlink label

… Hyperlink tags
attribute ：
href: must , Refers to the link jump address ;
target: Indicates how the link is opened .
_blank New window ,
_self This window （ Default ）
title： Text prompt properties

• Anchor point
  Anchor link ：
  1. Define an anchor point ：
     use Baidu Search
  2. Use anchors ：

  
  <a href="#a1"> Jump to the a1 It's about </a>
  

Tabular label

stay HTML In the document , Tables are widely used to store text and images on Web pages ;

• label :
  Tabular label :table
  Row labels :tr
  Cell ( Represents the concept of columns ):td
  Header :th : Bold and centered
  Table title :caption
  Label merging :
  merger :rowspan
  columns :colspan
• Common attributes of label :
  border: Frame
  width: Width
  height: Height
  algin: Alignment mode
  center,left,right

Form labels

Common properties ：
action attribute : Target address for submission (URL)
method attribute : submission :get( Default ) and post
get The way :
URL The address bar can be seen
The length is limited
Relatively unsafe .
post The way :
URL The address is not visible
The length is unlimited
A relatively safe .

Form item labels

Form item labels input Define input fields , Users can enter data in it .
stay HTML 5 in ,type Attributes have a lot of new values .

Drop down list label

<select>...</select> Tag create drop-down list .
name attribute : Definition name , Used to store drop-down values
size： Define the number of visible items in the menu ,html5 I won't support it
disabled When the attribute is true when , The menu will be disabled .
multiple multi-select
<option>... </option> Drop down selection tab , For embedding into <select> Used in the label ;
*value attribute : The value of the dropdown
*selected attribute : By default, drop-down the specified item .

Text field labels

… Multi line text input area
name : Definition name , Used to store values in the text area .
cols ： Specifies the number of columns visible in the text area .
rows ： Specifies the number of lines visible in the text area .
disabled： Whether to disable
readonly： read-only

Button label

<button>...</button> Label definition button .
<fieldset> --fieldset Element to group related elements in the form .

html Embedded frame

<iframe> The tag is created to contain another html File inline framework ( That's the inside frame ),
src Property to define another html Reference address of the document
frameborder Property defines the border ,
scrolling Whether the property definition has a scroll bar ,