React如何将组件渲染到指定节点—ReactDOM.createPortal（层级覆盖问题处理）

import React, { FC, useState, useEffect } from 'react'
import { useDispatch, useSelector } from 'react-redux'
import './index.less'

interface IProps {}

const ProductNum: FC<IProps> = (props: IProps) => {
    const _dispatch: any = useDispatch() || {}
    const { updateField } = _dispatch?.businessDetails
    const { data } = useSelector((state: any) => state.details)
    const el: HTMLElement = document.getElementById('root') as HTMLElement
    useEffect(() => {
        updateField({ count: 12 })
        // eslint-disable-next-line
    }, [isInsurance, deviceSnList])

    return (
        <>
            {ReactDom.createPortal(<div>要渲染的dom</div>,el)
        </>
    )
}

export default ProductNum