[Node.js] Node Util Promisify - How to Convert Callback Based APIs to Promise-based

转载于 2017-08-18 02:14:00 发布 · 111 阅读

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本文介绍如何使用Node.js V8.0+版本中新增的util库中的promisify函数将基于回调的函数转换为基于Promise的函数。通过具体示例展示了如何将crypto模块中的randomBytes函数从回调式改为Promise式，简化了异步操作的处理。

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Since Node.js V8.0+, it introduces a 'util' libaray, which has a 'promisfy' function.

It can conver a callback based function to promise based function:

const util = require('util');
const crypto = require('crypto');

// convert a callback based code to promise based
const randomBytes = util.promisify(
  crypto.randomBytes
);

/* Example of callback based code
crypto.randomBytes(32, (err, num) => {
  console.log(num);
});
*/

// Since randomBytes function now is promise based
randomBytes(32)
  .then(num => console.log(num))
  .catch(err => console.error(err));