//promise解決回調地獄問題
function eat(fn) {
setTimeout(() => {
fn('吃飯')
}, 2000)
}
function xizao(fn) {
setTimeout(() => {
fn('洗澡')
}, 1000)
}
eat(function (data) {
console.log(data)
xizao(function (data) {
console.log(data)
xizao(function (data) {
console.log(data)
xizao(function (data) {
console.log(data)
})
})
})
}
)
//異步函數的調用會產生回調地獄，代碼會像一坨屎
function eat() {
return new Promise((resolve) => {
setTimeout(() => {
resolve('吃飯')
}, 2000)
})
}
function xizao() {
return new Promise((resolve) => {
setTimeout(() => {
resolve('洗澡')
}, 1000)
})
}
//通過Promise的then方法解決回調地獄問題，代碼會變成一行一行的，不會嵌套
eat().then((res) => {
console.log(res + '1')
return xizao()
}).then((res) => {
console.log(res + '1')
})
//通過async，await函數將異步函數以同步的形式執行
async function run() {
let eat1 = await eat()
console.log(eat1 + '2')
let xizao1 = await xizao()
console.log(xizao1 + '2')
}
run()
