What is the use of the from tag in html

In HTML, the from tag is used to create an HTML form (form field) for user input to collect and transfer user information. All content in the form will be submitted to the server; the syntax "Form control". A form can contain one or more form elements, such as input, select, and textarea.

The operating environment of this tutorial: Windows 7 system, HTML5 version, Dell G3 computer.

html5 form tag

Function: The form tag is used to create an HTML form (form field) for user input to realize the collection and delivery of user information. In the form All content will be submitted to the server.

The form form field can contain various interactive controls - control labels (text fields, check boxes, radio boxes, submit buttons, etc.), such as , , < ; select>, and other tags.

Tag syntax format

<form action="提交地址" method="提交方式" name="表单名称">
  各种表单控件
</form>

• name: Just name the form, used for js technology.

• action: Set which file the form data is submitted to, used for back-end technology (such as php) to accept and process the data

• method : Set the data submission method, which is used to select the appropriate submission (transmission) method according to different data requirements

methodThe four commonly used submission methods:

get    		一般用来查询信息
post		一般用来新增信息
put      	一般用来修改信息
delete		一般用来删除信息

The difference between post and get:

• Data submission method, get can see the submitted data URL, but post cannot see it

• get is generally used For submitting a small amount of data, post is used to submit a large amount of data.

• get can submit up to 1K data. Post has no limit in theory.

• get can submit data In the browser history, security is not good

A complete form contains three basic components:Form tag, form field, form button.

1. Form tag

refers to the form tag itself, which is an area containing form elements, using the definition

2. Form field

is used to collect each item of user input in the tag. It is usually defined by the input tag. There are different types of input tags, corresponding to different user data. (For example: text field, drop-down list, radio button, check box, etc.)

3. Form button

is used to submit all the information in the form to the server

*表单域和表单按钮都属于表单元素。

Single line text box<input type="text">The default value is type="text"

Password box<input type="password">　

Radio button<input type="radio" name="">

Check box<input type="checkbox">

Hidden field<input type="hidden">

File upload<input type="file">

Drop-down box<select>Label</select>

Multi-line text<textarea></textarea>

Submit button<input type="submit">

Normal button<input type="button">

Reset button<input type="reset">

Control label:

input tag

• The meaning of input
• <input>The tag is a single tag
• type attribute sets different attribute values ​​to specify different control types
• In addition to the type attribute, there are other attributes

type="text" For the ordinary input box, the value is the value inside. The name and id will be used when writing js.

        &lt;input&gt;     

input tag Some attributes:

The checked attribute is only available for radio buttons and check boxes

属性	属性值	描述
type	Text	单行文本输入框
	Password	密码输入框
	Radio	单选按钮
	Checkbox	复选框
	Button	普通按钮
	Submit	提交按钮
	Reset	重置按钮
	Image	图像形式的提交按钮
	File	文本域
name		空间的名称
value		input控件中的默认文本值
size		input控件在页面中的显示宽度
checked		定义选择空间默认被选中的项
Maxlength		控件允许输入的最多字符数

密码框

<input>

单选框

name相同的单选框智能选择一个

        男 <input> 
        女 <input>

复选框

多选框可以选取多个

        爱好： 
 
        抽烟<input> 
        喝酒<input> 
        烫头<input>

按钮

普通按钮可以根据需求来用js添加功能

提交按钮会把输入的表单信息提交到form表单的action地址

重置按钮会把表单信息重置为默认

        &lt;input&gt;         &lt;input&gt;         &lt;input&gt;     

下拉框标签

下拉框标签有点特殊，不是input的属性而是一个单独的标签

        <select>
            <option>山东</option>
            <option>北京</option>
            <option>江苏</option>
            <option>深圳</option>
            <option>上海</option>
        </select>

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