1.syntax 语法:functional component语法更简单,只需要传入一个props参数,返回一个react片段。class component 要求先继承React.Component然后常见一个render方法,在render里面返回react片段。下面是两者被Babel编译过的代码 2.state 状态:因为function component 知识一个普通的函数所以不可以在其中用this.state , setState(...
function MyButton() { const [count, setCount] = useState(0); function handleClick() { setCount(count + 1); } return ( Clicked {count} times ); } React will call your component function again. This time, count will be 1. Then it will be 2. And so on. If you render the sa...
a simpler syntax for writing these kinds of components was introduced, and we began calling these components "stateless functional components". In this lesson, let's take a look at how to define a stateless function component, and
class App extends React.Component { render() { return <Toolbar theme="dark" />; } } function Toolbar(props) { // The Toolbar component must take an extra "theme" prop // and pass it to the ThemedButton. This can become painful ...
If you're using class-based components instead of function components, change extends `React.Component` to extends `React.PureComponent` to get the same effect. 如果您使用基于类的组件,请向类添加方法并在构造函数中使用bind函数以确保它可以访问组件实例。
Create a Function component calledCar functionCar(){returnHi, I am a Car!;} Rendering a Component Now your React application has a component called Car, which returns anelement. To use this component in your application, use similar syntax as normal HTML:<Car /> Example Display the...
class App extends React.Component { render() { let data = { name: 'xhs-rookies', age: 18, skills: ['JavaScript', 'React', 'Webpack'], test1: null, test2: undefined, flag: false, friend: { name: 'xhs-zymxxxs', age: 29, ...
支持annotation、infer、syntax、all,当你只需要在某些组件或hooks中优化时,可以使用annotation模式,并在组件或hooks中添加use memo注释。 javascript constReactCompilerConfig={compilationMode:'annotation',// annotation | infer | syntax | all};// src/app.jsxexportdefaultfunctionApp(){'use memo';// ...}...
For non-arror function component: functionPerson(props:PersonProps):React.ReactElement{return({props.username})} there are no errors, but I want to use arrow func with generic type FunctionComponent. For that case, type of props should be inferred fromReact.FunctionComponent<PersonProps> ljharb...
首先,这其实是一道没有意义的面试题,我们完全不需要依赖这个特性,如果我们需要依赖状态更新后的值,对于 class component 可以在 componentDidMount 和 componentDidUpdate 中来执行;对于 function component 可以在 useEffect 的回调函数中执行 其次,对于不同模式下的 React 效果不同(https://17.reactjs.org/docs/conc...