以下代码输出顺序是：
setImmediate(() => {
console.log(1);
Promise.resolve().then(() => {
console.log(2);
});
}, 0);
new Promise((resolve) => {
console.log(3);
resolve();
}).then(() => {
console.log(4);
process.nextTick(() => {
console.log(5)
});
setTimeout(() => {
console.log(6);
}, 0);
}).then(() => {
console.log(7);
});
console.log(8);