Implement Promisify

mediumJS SpecificJS / TS3 tests

Problem Statement

Implement `promisify(fn)`, which takes a Node.js-style asynchronous function that expects an error-first callback `(err, result) => void` as its last argument, and returns a function that returns a Promise.

Examples

Example 1:
function readFile(filename, callback) {
  if (!filename) callback(new Error('No file'));
  else callback(null, 'file content');
}
const readFileAsync = promisify(readFile);
const data = await readFileAsync('test.txt'); // 'file content'

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Implement Promisify

Problem Statement

Examples

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