Node.js fs.access 无论如何都会返回 undefined

Question

Here's the code:

import * as path from 'path';
import * as fs from 'fs';

const doesPathExist = async (path: string) => {
  return await fs.access(path, fs.constants.R_OK, (err) => {
    return err ? false : true;
  });
};

const someFunc = async (documentName: string) => {
  const documentPath = path.join(__dirname, documentName);
  const pathExists = doesPathExist(documentName);
};

The function doesPathExist seems to return Promise<void> , making the pathExists variable undefined no matter the outcome. I've tried initializing a temp variable at the top of the function before running fs.access and changing its value inside the callback but still no luck.

Answer 1

The issue is with fs.access , this function does not return a Promise or anything else.

There are a few options to solve it.

1. you can always use fs.accessSync()

const doesPathExist = async (path: string) => {
  try {
    fs.accessSync(path, fs.constants.R_OK)
    return true
  } catch (e) {
    return false
  }
};

2. Use fs.promises

const fsPromises = fs.promises;

const doesPathExistB = async (path: string) => {
  try {
    await fsPromises.access(path, fs.constants.R_OK)
    return true
  } catch (e) {
    return false
  }
};
// OR
const doesPathExistA = async (path: string) => {
  return new Promise(async (resolve) => {
    await fsPromises.access(path, fs.constants.R_OK)
      .then(() => resolve(true))
      .catch(() => resolve(false))
  })
};