两个周末都搭在promise上面啦，所以总结一下吧。
promise1
promise2
error
promise1
promise2
success
error
setTimeout(() => {
console.log(‘once’)
resolve(‘success’)
}, 1000)
a = new Promise((resolve, reject) => {
setTimeout(() => {
console.log(‘once’)
resolve(‘success’)
}, 1000)
console.log(555)
})
console.log(12333)
v = Date.now()
a.then((res) => {
console.log(res, Date.now() - v)
})
a.then((res) => {
console.log(res, Date.now() - v)
})
setTimeout(() => {
console.log(9999)
})
new Promise((resolve, reject) => {
resolve(3)
}).then(a => {
console.log(a)
})
setTimeout(() => {
console.log(1)
})
new Promise((resolve, reject) => {
console.log(2);
resolve(3)
}).then(res => {
console.log(res)
})
console.log(4)
