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[英]How to convert a React class-based component into a functional component?
[英]React.js: How to convert class based component to functional?
我正在使用基于函数的组件构建应用程序。 我在类中找到了Material Ui的侧边栏菜单模板,并希望将其转换为功能组件。 但转换点击按钮后不起作用。 我只是将菜单图标更改为另一个。 任何帮助将不胜感激。
这是类中的默认组件
import React from "react";
import AppBar from "@material-ui/core/AppBar";
import Toolbar from "@material-ui/core/Toolbar";
import Typography from "@material-ui/core/Typography";
import Button from "@material-ui/core/Button";
import IconButton from "@material-ui/core/IconButton";
import MenuIcon from "@material-ui/icons/Menu";
import { NavDrawer } from "./NavDrawer";
class NavBar extends React.Component {
constructor(props) {
super(props);
this.state = {
drawerOpened: false
};
}
toggleDrawer = booleanValue => () => {
this.setState({
drawerOpened: booleanValue
});
};
render() {
return (
<div className="App">
<AppBar position="static">
<Toolbar>
<IconButton
color="secondary"
aria-label="Menu"
onClick={this.toggleDrawer(true)}
>
<MenuIcon />
</IconButton>
<Typography variant="h6" color="inherit">
News
</Typography>
<Button color="inherit">Login</Button>
</Toolbar>
</AppBar>
<NavDrawer
drawerOpened={this.state.drawerOpened}
toggleDrawer={this.toggleDrawer}
/>
</div>
);
}
}
export default NavBar
在这里,我正在尝试转换
import React, { useState } from 'react'
import AppBar from '@material-ui/core/AppBar'
import Toolbar from '@material-ui/core/Toolbar'
import Typography from '@material-ui/core/Typography'
import IconButton from '@material-ui/core/IconButton'
import NavDrawer from './NavDrawer'
import AddShoppingCartIcon from '@material-ui/icons/AddShoppingCart'
function NavBar(props) {
const [drawerOpened, setDrawerOpened] = useState(false)
const toggleDrawer = booleanValue => () => {
setDrawerOpened(booleanValue)
}
return (
<div className="App">
<AppBar position="static">
<Toolbar>
<IconButton
aria-label="AddShoppingCartIcon"
onClick={() => toggleDrawer(true)}
>
<AddShoppingCartIcon style={{ fontSize: 30 }} color="secondary" />
</IconButton>
<Typography variant="h6" color="inherit"></Typography>
</Toolbar>
</AppBar>
<NavDrawer drawerOpened={drawerOpened} toggleDrawer={toggleDrawer} />
</div>
)
}
export default NavBar
您可以这样做来代替切换操作。
const toggleDrawer = () => {
setDrawerOpened(!drawerOpened)
}
而在回报
onClick={toggleDrawer}
您的功能正在堆叠。 在 onclick 上,您尝试调用函数来调用函数。 只需使用 const 代替。
在toggleDrawer const 上,您应该将setDrawerOpened 设置为与获得切换效果相反的值。
看看 React hooks,有两种方法:
const [toggleDrawer, setToggleDrawer] = useState(false); // set variable
<button onClick={() => setToggleDrawer(!toggleDrawer}>
您可以在组件初始渲染后使用 useEffect 执行一些逻辑,以防止出现最大错误:
const toggleDrawer = false;
useEffect(() => { // update variable
checkDrawOpened(toggleDrawer)
}, toggleDrawer);]
With the one click
onClick={toggleDrawer} // use variable
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