promise 链式

let send = (item) => Promise.resolve(`此时参数是：（${item}）`)

async function init(){
    const arr = [1,2,3,4,5]
    let res = 0
    await arr.forEach(item=>{
        send(item).then(e=>{
            console.log(e)
            res++
            console.log(res)
        })
    })
    console.log(res)
}

init()