Help in serializing AST to JavaScript

[peter17]

Hi!

I have a JSON file which is a estree AST. I need to serialize it to JavaScript.

I am trying to use https://github.com/syntax-tree/estree-util-to-js for this, but I am not a JavaScript developer and I don't understand how to have the example code run... (copied below from the README):

import fs from 'node:fs/promises'
import {parse} from 'acorn'
import {toJs} from 'estree-util-to-js'

const file = String(await fs.readFile('index.js'))

const tree = parse(file, {ecmaVersion: 2022, sourceType: 'module', locations: true})

// @ts-expect-error: acorn is funky but it works fine.
console.log(toJs(tree))

I saved that code to test.js and I installed estree-util-to-js using NPM but when I run node test.js I get SyntaxError: Cannot use import statement outside a module

I copied the code to test.html and replaced a line with import {toJs} from 'https://esm.sh/estree-util-to-js@2?bundle' but I can't do the same for node:fs/promises...

Any help, please? Thanks a lot in advance. Best regards

[ChristianMurphy]

Welcome @peter17!
Sorry you ran into a spot of confusion.

SyntaxError: Cannot use import statement outside a module

This indicates you have the file marked as CJS.
You can mark it as ESM by either adding "type": "module" in your package.json (recommended) or changing the file extension to .mjs
you can find more information on enabling ESM here https://nodejs.org/api/esm.html#enabling

[peter17]

Hi @ChristianMurphy

Thank you very much! It is working fine, now, with node test.js!

Best regards