react的use函数可搭配Suspense与lazy

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use 是一个用于解析 React v18 及以下版本的 promise 状态的 polyfill hook。请注意，它只实现了消费 promise 的能力。

参考资料

https://www.reactuse.com/zh-Hans/state/usehttps://zh-hans.react.dev/reference/react/use#dealing-with-rejected-promises

app.jsx 

import { useState, Suspense, lazy } from 'react';const Son = lazy(() => delayForDemo(import('./Son.jsx')));function fn1() {return new Promise((res) => {setTimeout(res, 1000, { a: { b: 33 } })})
}
async function fn2() {var res = await new Promise((res) => {setTimeout(res, 1000, 'bbbb')})return res
}
export default function MarkdownEditor() {const [dt1, sets] = useState(fn1);const [dt2, setb] = useState(fn2);return (<><Suspense fallback={<div>loading...</div>}><h2>Preview</h2><Son dt1={dt1} dt2={dt2} /></Suspense></>);
}// Add a fixed delay so you can see the loading state
function delayForDemo(promise) {return new Promise(resolve => {setTimeout(resolve, 1200);}).then(() => promise);
}

son.jsx

import { use } from 'react'
export default function MarkdownPreview({ dt1, dt2 }) {var d1 = use(dt1)var d2 = use(dt2)return (<><h1>{dt1.a.b}</h1><div>-------</div><h1>{d2}</h1></>);
}

只有等待fn1,fn2里的函数 resolve之后,才会显示Son组件

附:延迟promise时间

延迟特定promise时间
function delay(ms) {return new Promise(resolve => setTimeout(resolve, ms));
}delay(3000).then(() => alert('runs after 3 seconds'));

 附:延迟组件加载时间

//定义
function delayForComp(promise) {return new Promise(resolve => {setTimeout(resolve, 1200);}).then(() => promise);
}//使用:
import { useState, Suspense, lazy } from 'react';const Mxxxxx = lazy(() => delayForComp(import('./Mxxxxx.jsx')));//放在Suspense内部return (<><Suspense fallback={<div>loading...</div>}><h2>Preview</h2><Mxxxxx dt1={dt1} dt2={dt2} /></Suspense></>);

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