What is the difference between name, id and class in HTML?

This time I will show you what is the difference between name, id, and class in HTML. How to use name, id, and class? What are the precautions when using name, id, class? The following is a practical case, let’s take a look.

name

Specify the name of the label.

Format

<input type="text" name="username" />

Application scenarios

①form form: name can be used as the variable name of the form list transferred to the server; as above, it is transferred to the server The name is: username='text value'.

②Input type='radio'Radio label: When the names of several radio label are set to the same value, a radio selection operation will be performed.

<input type="radio" name=&#39;sex&#39;/>男
<input type="radio" name=&#39;sex&#39;/>女

③Quickly obtain a group of tags with the same name: Get tags with the same name and perform operations together, such as: changing attributes, registering events, etc.

function changtxtcolor() {
    var txts = document.getElementsByName('txtcolor'); //获取所有name=txtcolor 的标签
    for (var i = 0; i < txts.length; i++) { //循环遍历标签，并把背景色改为red
        txts[i].style.backgroundColor = &#39;red&#39;;
    }
}

Characteristics

The value of the name attribute is not unique in the current page.

id

Specifies the unique identifier of the tag.

Format

<input type=password  id="userpwd" />

Application Scenario

①Quickly obtain the label object based on the unique id number provided. For example: document.getElementById(id)

② Used as the value of the label label for attribute: Example: User name: , indicating click this When labeling, the label whose id is userid gets focus.
Features

The value of the id attribute must be unique in the current page.

class

Specify the class name of the label.

Format

<input type=button class="btnsubmit" />

Application Scenario

①CSS operation, put some specific styles into a class class, if you need tags of this style, you can add this class.

Features

You can put multiple classes in one class attribute, but they must be separated by spaces; such as: class='btnsubmit btnopen'

I believe I read it You have mastered the methods in these cases. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Related reading:

How to insert a video into an HTML webpage

How to use HTML+CSS to make a mouseover You can display the secondary menu bar

How to solve the gap in the picture in H5

The above is the detailed content of What is the difference between name, id and class in HTML?. For more information, please follow other related articles on the PHP Chinese website!