# 2621. Sleep

###### tags:`Promise` | `leetCode`
<font color="#01AE9A" background="E1F3F0">`easy`</font>

### 題目
Given a positive integer millis, write an asyncronous function that sleeps for millis milliseconds. It can resolve any value.
### Example

Input: millis = 100
Output: 100
Explanation: It should return a promise that resolves after 100ms.
let t = Date.now();
sleep(100).then(() => {
  console.log(Date.now() - t); // 100
});

Input: millis = 200
Output: 200
Explanation: It should return a promise that resolves after 200ms.

---
### 解題邏輯
這題要我們回傳一個 promise，而 promise如果成功要做的事是在＿毫秒後,所以理論上就是 promise 裡setTimeout，設定＿毫秒後執行resolve

async function sleep(millis) {
   return new Promise(function(res,rej){
     try{
      setTimeout(res, millis);
     }catch(err){
       rej(err)
     }
   })
}

promise 因為有可能成功或失敗，因此用 try catch包起來