Using import fs from 'fs'

Question

I want to use import fs from 'fs' in JavaScript. Here is a sample:

import fs from 'fs'

var output = fs.readFileSync('someData.txt')

console.log(output)

The error I get when I run my file using node main.js is:

(function (exports, require, module, __filename, __dirname) { import fs from 'fs
'
                                                              ^^^^^^
SyntaxError: Unexpected token import

What should I install in Node.js in order to achieve importing modules and functions from other places?

Answer 1

For default exports you should use:

import * as fs from 'fs';

Or in case the module has named exports:

import {fs} from 'fs';

Example:

//module1.js

export function function1() {
  console.log('f1')
}

export function function2() {
  console.log('f2')
}

export default function1;

And then:

import defaultExport, { function1, function2 } from './module1'

defaultExport();  // This calls function1
function1();
function2();

Additionally, you should use Webpack or something similar to be able to use ES6 import

Answer 2

ES6 modules support in Node.js is fairly recent; even in the bleeding-edge versions, it is still experimental. With Node.js 10, you can start Node.js with the --experimental-modules flag, and it will likely work.

To import on older Node.js versions - or standard Node.js 10 - use CommonJS syntax:

const fs = require('fs');

Answer 3

In order to use import { readFileSync } from 'fs' , you have to:

1. Be using Node.js 10 or later
2. Use the --experimental-modules flag (in Node.js 10), eg node --experimental-modules server.mjs (see #3 for explanation of .mjs)
3. Rename the file extension of your file with the import statements, to .mjs , .js will not work , eg server.mjs

The other answers hit on 1 and 2, but 3 is also necessary. Also, note that this feature is considered extremely experimental at this point (1/10 stability) and not recommended for production, but I will still probably use it.

Here's the Node.js 10 ESM documentation .

Answer 4

Building on RobertoNovelo's answer:

import * as fs from 'fs';

is currently the simplest way to do it.

It was tested with a Node.js project (Node.js v10.15.3), with esm , allowing to use import .

Answer 5

The new ECMAScript module support is able natively in Node.js 12 🎉

It was released on 2019-04-23 and it means there is no need to use the flag --experimental-modules .

To read more about it:

The new ECMAScript module support in Node.js 12

Answer 6

Go to package.json file and add:

"type": "module"

This worked for me!

Answer 7

If you want your statement import fs from 'fs' to be executable, you can make your file extension.mjs instead of.js. ie filename.mjs

Answer 8

目前还不支持...如果你想使用它，你必须安装Babel 。

Answer 9

hey friends node js use commonjs not modaljs so use alawys use const fs = require('fs') for file system if we use modaljs import fs from 'fs' its give error se in termile import {fs} from 'fs'; ^^^^^^ SyntaxError: Cannot use import statement outside a module

Answer 10

如果我们使用的是 TypeScript，我们可以通过从终端或命令提示符运行命令npm install @types/node来更新类型定义文件。