Can’t import fs Promises API with ECMAScript Modules

[dieulot]

• Version: v10.2.1
• Platform: Windows 10 64-bit
• Subsystem: fs

Per the docs, “The API is accessible via require('fs').promises.”

When using ECMAScript Modules it can’t be accessed like that. One may expect to be able to load it with import {promises as fs} from 'fs', but this gives an error.

import {promises as fs} from 'fs'
        ^^^^^^^^
SyntaxError: The requested module 'fs' does not provide an export named 'promises'
    at ModuleJob._instantiate (internal/modules/esm/module_job.js:89:21)

So right now accessing the fs Promises API directly when using ECMAScript Modules requires two lines, like so:

import {default as fsWithCallbacks} from 'fs'
const fs = fsWithCallbacks.promises

[devsnek]

it's an experimental API so the esm loader doesn't attach it as a named export.

[dnalborczyk]

@dieulot here is a related discussion: #20504

[jdalton]

@dieulot I'm going to close this issue since has been answered. Feel free to ping back though for anything.

[rektide]

Ideally I could:
import {readFile} from 'fs/promise

The opening ask would be only mildly ghastly & ugly, getting a complete 'fs' import.

[devsnek]

the original design of fs promises was as you mention it. I'm hopeful it can be restored.

[rektide]

Talked with @jdalton some on twitter. He's intending to switch his standard-things/esm project over to exposing non-enumerable properties. This won't make import {readFile} from '[something-or-other]' possible (which would be the most natural & desireable in the EcmaScript module world) but it should mean we can at least import {promises} from 'fs' which is better than where we are now.

[paddotk]

@jdalton I'm using Node 10.16.0 and this still doesn't work for me.

Trying the following:

const fs = window.require('fs'); // Works
const fsPromises = window.require('fs').promises; // Nope

or

const fs = window.require('fs');
const fsPromises = fs.promises; // Nope

or

const fsPromises = window.require('fs/promises')

all doesn't work for me.

Since I need to specify window (or global), I can't use an import statement either. I'm using (the latest version of) Electron although I doubt this makes any difference..

[samdutton]

const fsPromises = require('fs').promises; works for me.

[michaelbrawn]

const fsPromises = require('fs').promises; works for me.

Unfortunately, in TS, ES6, ESLint, await/async land with @typescript-eslint/no-require-imports enabled, this workaround isn't ideal.

Still waiting on something as simple as

import { readFile } from 'fs/promises'

or

import { readFile } from 'fs.promises'

or best yet,

import { readFileAsync } from 'fs'