async-iife.js

// hello / world 依序執行
async function hello(){ await new Promise((res)=> setTimeout(()=>{console.log("hello"); res();}, 2000) ) }
async function world(){ await new Promise((res)=> setTimeout(()=>{console.log("world"); res();}, 2000) ) }

console.log("start")
await hello()
await world()
console.log("end")

// hello / world 同時執行
let helloTask = (async function hello(){ await new Promise((res)=> setTimeout(()=>{console.log("hello"); res();}, 2000) ) })()
let worldTask = (async function world(){ await new Promise((res)=> setTimeout(()=>{console.log("world"); res();}, 2000) ) })()

console.log("start")
await helloTask
await worldTask
console.log("end")

// 個人覺得比較好的並行寫法 (參考google文件教學)
async function hello(){ await new Promise((res)=> setTimeout(()=>{console.log("hello"); res();}, 2000) ) }
async function world(){ await new Promise((res)=> setTimeout(()=>{console.log("world"); res();}, 2000) ) }

console.log("start")
let helloTask = hello()
let worldTask = world()
await helloTask
await worldTask
console.log("end")