HTML form study notes

What is a form?

A web form can send the data entered by the user to the server for processing. Because Internet users fill out forms using checkboxes, radio buttons, or text fields, WebForms resemble files or databases. For example, WebForms can be used to enter shipping or credit card information for ordering products, or can be used to retrieve data (eg, search on a search engine). Simply put, it is to collect user information

This is a form

Workflow of the form: The user opens the page—>fills in the form and submits—>packages it according to the corresponding method and sends it to the server—>the server receives it and transfers it to the corresponding program for processing

Basic

Framework : Add form elements under form

Form input tag Syntax:

Attribute : Name: name, the server identifies it by name Group, the same group needs the same name

Maxlength: Specify the maximum length of the input

Size: The size of the text box, in characters, the default is 20

value: default value, content submitted to the server

placeholder: prompt text

type:

text: input text, attribute:

password: Password box, the password will be automatically hidden

file: upload file, the displayed content is related to the browser

radio: radio button, the options that require radio selection need to use the same name, and will be returned value to the server to identify what is selected, add checked to determine the default option.

Checkbox: Check box, similar to radio rules.

Button: Cooperate with js to provide action, the value button displays the content

Subm: Submit button, cooperate with js to send the form in a form to the server, the value button displays the content

Reset: Restore the form in a form to the default state, and the value button displays the content

Hidden: Hidden field, not visible to the user, pass the value to the server.

Image: Image domain submission, the same function as submit, src contains the image address.

Drop-down menu and list label Syntax

Selected content

Option attributes:

Size: The displayed quantity. If it is greater than 1, it will be displayed in list form.

# ;To group the options

# Multi-line text field

is basically the same as the text of , more The cols and rows attributes are added. row controls the number of displayed rows, and cols displays the width. Attributes of form

action

: The destination, URL or server file sent by the form.

Method: Specify how to send the form to the server. There are two methods: get and post. The default is get GET: Use the URL as the passing parameter (the returned URL can see the form content), there are also limits on the amount of information sent, and are generally used to obtain user information.

POST: Form data is part of the HTTP request content. There is no limit on the amount of information sent. It is generally used to modify resources on the server. name: The name of the form.

Traget: Where to open the action URL Parameters: _blank, _self, _parent, _top

enctype: How to encode before sending the form, the parameters are: 1: Default method application/x-www -form-urlencoded 2:multipart / form-data 3:text / plain