行内样式

App.js

import React, { Component } from "react";

export default class ClassCom extends Component {
	render() {
		return (
			<div>
				<p style={{ color: "red", fontSize: "30px" }}>
					我是类组件-行内样式
				</p>
			</div>
		);
	}
}

外部样式

App.js

import React, { Component } from "react";
import "../asset/style.css";

export default class ClassCom extends Component {
	render() {
		return (
			<div>
				<p className={"waibu"}>我是类组件-外部样式</p>
			</div>
		);
	}
}

asset/style.css

.waibu{
  color: blue;
  font-size: 20px;
}

使用classname第三方模块

先安装classname

yarn add classname

App.js

import React, { Component } from "react";
import classname from "classname";
import "../asset/style.css";

export default class ClassCom extends Component {
	render() {
		return (
			<div>
				<p
					className={classname({
						waibu: true,
					})}
				>
					我是类组件-使用第三方模块classname
				</p>
			</div>
		);
	}
}

asset/style.css

.waibu{
  color: blue;
  font-size: 20px;
}

使用样式组件styled-component

先安装styled-components

yarn add styled-components

App.js

import React from 'react'
 import styled from 'styled-components'
 const Container = styled.div`
     width: 100px;
     height: 100px;
     background: #ccc;
 `
 class Hello extends React.Component{
     render () {
         return (
             {/* Container可以作为组件直接使用 */}
             <Container></Container>
         )
     }
 }