---
tags: blog
---

# JavaScript 實作題：`promisfy()`

## 題目

實作函式 `promisfy()`，將 callback function 轉換成回傳 Promise 的函式。

const mockFetch = (callback) => {
  setTimeout(() => {
    callback('api result')
  }, 1000)
}

const promisfy = () => { /* implement this function */ } 

const promisfied = promisfy(mockFetch)

promisfied.then(res => console.log(res))

## 參考解答

:::spoiler 點我

const mockFetch = (callback) => {
  setTimeout(() => {
    callback('api result')
  }, 1000)
}

const promisfy = (fn) => {
  return new Promise((resolve) => fn(resolve))
} 

const promisfied = promisfy(mockFetch)

promisfied.then(res => console.log(res))

:::