function Gen(time) {
    return new Promise(function(resolve, reject) {
        setTimeout(function() {
            resolve(time)
        }, time)
    })
}

async function test() {
    let arr = [Gen(2000), Gen(100), Gen(3000)]
    for await (let item of arr) {
        console.log(Date.now(), item)
    }
}

test()
// 1560092345730 2000
// 1560092345730 100
// 1560092346336 3000