通过vue学习react(四)|通过vue学习react(四) - watch,computed,slot等功能

这些功能都比较简单些, 通过react hooks和react class都进行了实现
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react 实现 watch
react hook 实现 watch

function useWatch(deps: T, handler: (next: T, prev: T) => void, immediate = false) { let nextRef = useRef(); const isImmediate = useRef(true); useEffect(() => { if (isImmediate.current) { handler(nextRef.current as T, deps); } else { isImmediate.current = true; } return () => { nextRef.current = deps; }; }, [deps]); } # 使用 let [count, setCount] = useState(0); useWatch(count, (next: typeof count, prev: typeof count) => { console.log(next, prev); });

react 类写法 实现 watch
class Watch extends React.Component { state = { count: 0 }; constructor(props: FC) { super(props); } setCount() { this.setState({ count: this.state.count + 1, }); }componentDidUpdate(_prev: any, prevState: typeof this.state) { console.log(prevState.count, this.state.count); }render() { return (); } }

react 实现 插槽(slot)
react hooks版本
function Child({ children }: { children: React.ReactNode }) { return (child {children}); }export default function Slot() { return (2333
); }

react 类写法
class Child extends React.Component { render() { const { children } = this.props; return (child {children}); } }class Name extends React.Component { constructor(props: React.FC) { super(props); }render() { return ( 2333
); } }

react 实现 computed
react hooks版本 通过useMemo模拟即可
export default function Computed() { let [count, setCount] = useState(0); const getCount = useMemo(() => { return count * 2; }, [count]); return ({getCount} ); }

react 类写法
原理则是每次setState都会触发render, 然后重新获取newCount
class Name extends React.Component { state = { count: 0 }; constructor(props: React.FC) { super(props); } get newCount() { return this.state.count + 1; }render() { return (【通过vue学习react(四)|通过vue学习react(四) - watch,computed,slot等功能】{this.newCount}
); } }

react 实现 v-model
react hooks版本
interface formProps { name?: string; age?: string; }export default function Model() { const [form, setForm] = useState({}); const handleChange = useCallback((e: ChangeEvent, key) => { setForm((raw) => ({ ...raw, [key]: e.target.value })); }, []); function onClick() { console.log(form); } return ( handleChange(e, "name")} /> handleChange(e, "age")} /> ); }

react 类写法
interface formProps { name?: string; age?: string; } class Model extends React.Component { constructor(props: React.FC) { super(props); this.state = { form: {} }; } handleChange(e: React.ChangeEvent, key: string) { this.setState({ form: { ...this.state.form, [key]: e.target.value }, }); }onClick = () => { console.log(this.state.form); }; render() { const { form } = this.state; return ( this.handleChange(e, "name")} /> this.handleChange(e, "age")} /> ); } }

react 实现 css scoped
css module
# index.module.css .app { color: aqua; flex: 1; } # Css.tsx import Style from "./index.module.css"; export default function Css() { return (我是一个字段
); }

css in js (emotion) 安装
npm i @emotion/styled @emotion/react

使用
/* @jsxImportSource @emotion/react */ import styled from "@emotion/styled"; import { css } from "@emotion/react"; import Style from "./index.module.css"; const base = css` color: #ee298c; `; const Container = styled.div` padding: 23px; &:hover { color: ${(props) => props.color}; } `; export default function Css() { return ( 我是一个字段
test
23333
);

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