Simple solution asleep with promise
Code


# Code
```javascript []
/**
 * @param {number} millis
 * @return {Promise}
 */
async function sleep(millis) {
   return await new Promise((resolve, reject) => {
    setTimeout(() => resolve(), millis)
   }); 
}

/** 
 * let t = Date.now()
 * sleep(100).then(() => console.log(Date.now() - t)) // 100
 */
```
['JavaScript']