css: What is the difference between class and id in div?
1. class is the class that sets the label, and the class attribute is used to specify which style class the element belongs to.
For example, you can add .content1 { color: red; background: #ff80c0 } to the style sheet. How to use: class="content1" .
id is the identifier of the set label . The id attribute is used to define a unique style of an element. For example, a CSS rule #content2 { font-size: larger } is used as follows: id="content2"
The concepts are different (the following two sentences are still comparable Insightful):
Class is a style, which must be defined first, and then can be applied to multiple structures/contents.
Easy to reuse. In other words, the class names can be the same.
id is a label used to distinguish different structures and contents, just like your name. If there are two people with the same name in a room, confusion will occur ;ID is to find the structure/content first, and then define the style for it;
2. Attribute priority issue
The priority of id is higher than class. You can write an example yourself. Part of the code is as follows ( is written by me, not the original author ):
##
<html>
<head>
<style type="text/css">
#aa
{
color:red
}
.aa
{
color:blue
}
</style>
</head>
<body>
<p id="aa" class="aa">I love you.</p>
</body>
</html>3. About js
If you want to perform script operations (js) on an object in the page, you can define an id for it. Otherwise, you can only use traversing the page elements and specifying specific attributes. It is a relative waste of time and resources to find it, and it is far less simple than an ID.
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