promise、async和await之执行顺序

async function async1(){
    console.log('async1 start')
    await async2()
    console.log('async1 end')
}
async function async2(){
    console.log('async2')
}
console.log('script start')
setTimeout(function(){
    console.log('setTimeout') 
},0)  
async1();
new Promise(function(resolve){
    console.log('promise1')
    resolve();
}).then(function(){
    console.log('promise2')
})
console.log('script end')

// script start
// async1 start
// async2
// promise1
// script end
// promise2
// async1 end

// setTimeout