Export issues?

[z3dev]

I have a small package that has this code.

import fs from 'fs'

import opentype from "opentype.js"

/**
 * Load the font description from the given file path.
 * @param {String} path - path to local file, i.e. font
 * @returns {Font} new font object which contains the contents of the font
 */
export const loadFont = (path) => {
  return opentype.parse(fs.readFileSync(path))
}

/**
 * Load the font description from the given data.
 * @param {ArrayBuffer} data - raw data from font file
 * @returns {Font} new font object which contains the contents of the font
 */
export const loadFontFromData = (data) => {
  return opentype.parse(data)
}

However, when I try to rollup the package into a combined distribution, rollup say...

npm run build

> jscad-text@4.0.0 build
> rollup --config


./src/index.js → ./dist/jscad-text.umd.js, ./dist/jscad-text.js...
[!] RollupError: src/loadFont.js (3:7): "default" is not exported by "node_modules/opentype.js/dist/opentype.mjs", imported by "src/loadFont.js".
https://rollupjs.org/troubleshooting/#error-name-is-not-exported-by-module
src/loadFont.js (3:7)

This seems to be an issue with the packaging.

[ILOVEPIE]

The package was incorrectly released as version 1.3.5. The correct version number is 2.0.0. There are Major breaking changes.

[Jolg42]

Version 2.0.0 is now available (#837 (comment))

The 1.3.5 version should be ignored, it was meant to be published as 2.0.0 but got published as 1.3.5 by mistake.
As of May 6th 2026 the latest v1 release is v1.3.4.

[z3dev]

V2.0.0 didn't help anything. Same error.

> rollup --config


./src/index.js → ./dist/jscad-text.umd.js, ./dist/jscad-text.js...
[!] RollupError: src/loadFont.js (3:7): "default" is not exported by "node_modules/opentype.js/dist/opentype.mjs", imported by "src/loadFont.js".
https://rollupjs.org/troubleshooting/#error-name-is-not-exported-by-module
src/loadFont.js (3:7)
1: import fs from 'fs'
2: 
3: import opentype from "opentype.js"
          ^

Here's my take on builds.

• min versions are not necessary as the DSNs always minify
• if this is a module then set type in the package.json
• the dist/opentype.js should be 100% pure ES (let the DSNs minify)
• for NODE, point main at the source, i.e. index.js ??
• other dist formats are optional

And a small ESBUILD config (js) would make the package.json cleaner.

[z3dev]

FYI, I'm able to complete the rollup by making this simple change.

// FOR ROLLUP import * as opentype from "opentype.js"
import opentype from "opentype.js"

[ILOVEPIE]

Here's my take on builds.

* min versions are not necessary as the DSNs always minify

* if this is a module then set type in the package.json

* the dist/opentype.js should be 100% pure ES (let the DSNs minify)

* for NODE, point main at the source, i.e. index.js ??

* other dist formats are optional

This is Optionally a module. It's not expected you use DSNs. No, we'll minify it for those who want it, the original is in there too iirc. Node did have its main pointed at the source last I checked, someone messed with the build stuff so idk. We need other dist formats.

[z3dev]

I’m not sure. Why other formats? Those that want an old format can use babel or esbuild.

There are really only two environments to support… node and browsers

Node supports ES modules by default.
Modern browsers support ES modules.

Done.

[ILOVEPIE]

There's a lot of embedded devices that use older chromium versions, and a lot of electron and other apps that use old node versions.

[receter]

Maybe https://nodejs.org/api/packages.html#conditional-exports could help?

[kayahr]

This problem is quite annoying. When I upgraded to 2.0.0 I used import opentype from "opentype.js" in my ESM project. Node.js was happy, everyone was happy until the web devs used my library in an Angular application (with their insane angular-cli bundler stuff) which didn't like this import. So I switched to import { parse } from "opentype.js". Then it worked in Angular. But this import doesn't work with Node.js. I guess the whole problem is this stuff in package.json:

  "main": "./dist/opentype.js",
  "browser": "./dist/opentype.js",
  "module": "./dist/opentype.mjs",

Node.js treats this module as CJS because there is no "type": "module" in the package.json and main points to a CJS variant. Node.js doesn't use the non-standard "module" property. But looks like angular-cli DOES use that. So Angular sees an ESM library while Node.js sees a CJS library. And their export behaviour is not the same.

My current workaround is:

import * as opentype from "opentype.js";

const parse = opentype.parse ?? opentype.default.parse;

I recommend using conditional exports to CORRECTLY export CJS and ESM versions. I think the non-standard "browser" and "module" properties can still be used for older bundlers which do not support standard conditional exports for some reason.