- useEffect 执行后，回调函数立即执行
- 依赖的自变量变化后，回调函数立即执行
- 不需要显示指明依赖
import { useState, useEffect } from 'mini-hooks';
const [count, setCount] = useState(0);
useEffect(() => {
console.log('count: ', count());
});
useEffect(() => {
console.log('do nothing');
});
setCount(2);