Uncaught ReferenceError: m is not defined - Create React App - browserslist - Internet Explorer IE

[jirihajek]

Hi, I'm trying to replace mapbox-gl and while it works fine in the developer mode, it breaks down when compiled into production using standard react-scripts.

maplibre-gl-js version: 2.1.6

I just use it like:

import maplibregl from 'maplibre-gl';
import 'maplibre-gl/dist/maplibre-gl.css';

new maplibregl.Map({});

The map is properly drawn, but when compiled, I get error message:

Uncaught ReferenceError: m is not defined
    at 715727c0-8b17-4de1-9814-b138884d408b:1:6514

from the workers and nothing is drawn. I'm not sure it's a bug, I suppose I might be doing something wrong, but don't see anything obvious, as the same approach works with mapbox-gl. Thanks for any idea!

[HarelM]

No clue, try reproducing this in stackbliz.

[jirihajek]

I tried stackblitz, but it doesn't seem to be able to handle a 'build' command in order to test the production environment. Anyway, I created a trivial new project, just a clean create-react-app application with a simple map:

import { useEffect } from 'react';
import maplibregl from 'maplibre-gl';
import 'maplibre-gl/dist/maplibre-gl.css';
import './App.css';

function App() {
  useEffect(() => {
    const mbMap = new maplibregl.Map({
      container: 'map',
    });
    mbMap.setStyle('https://api.maptiler.com/maps/bright/style.json?key=******************');
  });

  return (
    <div className="App">
       <div style={{width: 400, height: 300}} id='map'/>
    </div>
  );
}

export default App;

And the result is the same: Works in development, but as soon as it's compiled using npm run build, there's the same runtime error and the map isn't drawn.

[HarelM]

I'm not familiar enough with react to understand the differences between dev and prod build.
I suggest to try and use the react library instead of writing your own...

[Kanahiro]

IMHO you should use useRef() to indentify HTMLDivElement.
Following is simple sample.

const Map: React.FC = () => {
    const mapContainer = useRef<HTMLDivElement | null>(null);

    useEffect(() => {
        if (!mapContainer.current) return;

        const map = new mapboxgl.Map({
            container: mapContainer.current,
            style: 'https://api.maptiler.com/maps/bright/style.json?key=******************',
        });
    }, []);
    return <div style={{ height: 800 }} ref={mapContainer} />;
};
export default Map;

Also, I think this wouldn't be a problem on maplibre-gl-js.

[jirihajek]

IMHO you should use useRef() to indentify HTMLDivElement.

Thanks, you're right that it's a cleaner approach, but tried it and it doesn't have any effect, the problem remains the same.

I'm not familiar enough with react to understand the differences between dev and prod build.

I'm not an expert in this field either, but afaik we are talking mostly just about webpack applied to the project. That's what I suppose many projects do and that's why I'm surprised that I'm the only one reporting this issue.

I suggest to try and use the react library instead of writing your own...

Do you mean any particular one? I'd give it a try, but to be honest, I don't see a reason why I'd get any different result after I apply webpack than I get in the sample project above. (not mentioning that I'm not sure I'd be able to use another library due to the ways I use the map - but that's beyond the scope of this issue and the sample project)

[HarelM]

The following is what I know is the goto when it comes to React:
https://github.com/visgl/react-map-gl
I've seen the following issue which seems to make sure maplibre is working with this library:
visgl/react-map-gl#1685
So I think people there are able to make maplibre work.
It might require some extra configuration, IDK...
If you know what causing this problem in this library feel free to send a PR. I'm not sure I know where to begin...

[jirihajek]

https://github.com/visgl/react-map-gl

I tried a simple project and I got the very same problem. For the reference, it's like this:

import * as React from 'react';
import Map from 'react-map-gl';
import maplibregl from 'maplibre-gl';

function App() {
  return <Map 
    mapLib={maplibregl} 
    style={{width: 600, height: 400}}
    mapStyle="https://api.maptiler.com/maps/bright/style.json?key=**************"
  />;
}

export default App;

If you know what causing this problem in this library feel free to send a PR. I'm not sure I know where to begin...

I tried to find out more. The development webpack build apparently works fine, but the production build is where it breaks. I tried to pinpoint the issue, used webpack without minification and the error message is now

Uncaught ReferenceError: _wrapNativeSuper is not defined

and after some search I found that it's from the ajax.ts:

export class AJAXError extends Error {
    /**
     * The response's HTTP status code.
     */
    status: number;

    /**
     * The response's HTTP status text.
     */
    statusText: string;

    /**
     * The request's URL.
     */
    url: string;

    /**
     * The response's body.
     */
    body: Blob;

    constructor(status: number, statusText: string, url: string, body: Blob) {
        super(`AJAXError: ${statusText} (${status}): ${url}`);
        this.status = status;
        this.statusText = statusText;
        this.url = url;
        this.body = body;
    }
}

Any idea?

[RowanTate]

I'm having the same issue. My guess it's something to do with how Create React App is doing its bundling/minifying. But I don't understand enough of how that process works

[RowanTate]

Digging a bit deeper in to this, it is related to what browser/js features are being targeted at (not sure the exact feature that causes the issue)
But I found if you change the browserslist being targeted in the package.json to something modern maplibre-gl works correctly.

This is why development builds work, but productions builds don't. Buy default CRA has a very wide browsers support for production but very restricted for development

For example if you change your browserslist to something like the following, this will make your production build work (at least for the latest version of chrome)
"browserslist": { "production": [ "last 1 chrome version" ],

Not sure what the best solution here is?

Would be good to know the exact feature that causes the change in the transpiling (ie what browsers we are unable to target)
Possibly related to class usage? https://babeljs.io/docs/en/babel-plugin-transform-classes

[wipfli]

Thanks for the hint about broswerslist. If I add internet explorer to the development section in my package.json, I get the ReferenceError also in development mode:

  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version",
+     "ie 11"
    ]
  }

[wipfli]

Note that MapLibre GL JS v2 dropped IE support altogether.

[wipfli]

I ended up using the following package.json

{
  "name": "maplibre-v2",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.16.2",
    "@testing-library/react": "^12.1.4",
    "@testing-library/user-event": "^13.5.0",
    "maplibre-gl": "^2.1.7",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-scripts": "5.0.0",
    "web-vitals": "^2.1.4"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
-     ">0.2%",
-     "not dead",
-     "not op_mini all"
+     "defaults",
+     "not ie 11"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}

Note that I use react-scripts@5.0.0. I had issues with lower versions.

[jirihajek]

Thanks for the updates, I can confirm that the change in targeted browsers really resolves the issue. In my case though, it was necessary to also include "not op_mini all", without this the issue was still there.

A note to anybody testing this: You might need to delete node_modules/.cache, otherwise the change in "browserslist" might not be applied.

That said, the underlaying cause of the issue is still unclear.

[ohrie]

I can confirm, that adding browserslist to package.json using ["defaults", "not ie 11"] fixed the issue in Gatsby 4.

[theweaklink]

Hi there,

I am getting a similar error y is not defined when building my app (made with create-react-app too). I followed this mapboxgl issue replacing the path to the correct maplibre-gl worker, but no luck.

• In dev (yarn start) => no issue at all, the map displays properly
• Without the worker-loader trick => creating a build (yarn build) in dev and production works however map does not display and y is not defined error is output
• With the worker-loader trick => the build doesn't go through

Module parse failed: 'import' and 'export' may appear only with 'sourceType: module' (1:0)
File was processed with these loaders:
 * ./node_modules/worker-loader/dist/cjs.js
 * ./node_modules/babel-loader/lib/index.js
 * ./node_modules/source-map-loader/dist/cjs.js
You may need an additional loader to handle the result of these loaders.
> export default function Worker_fn() {
|   return new Worker(__webpack_public_path__ + "static/js/maplibre-gl-csp-worker.10c64516.worker.js");
| }

I'm not sure if this is related to this issue (it looks like it overlaps?).
Thanks

[theweaklink]

Actually after fiddling a bit and crossing info from docs and github issues, I eventually got it to work in both dev and prod env. Here is what worked in case it helps anyone else:

package.json

    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
      "not op_mini all",
      "defaults",   # line added as mentionned above in this issue
      "not ie 11"   # line added as mentionned above in this issue
    ],

in App.js (or wherever the map import is)

// eslint-disable-next-line import/no-webpack-loader-syntax
import maplibregl from '!maplibre-gl';      // ! is important here
import maplibreglWorker from 'maplibre-gl/dist/maplibre-gl-csp-worker';

maplibregl.workerClass = maplibreglWorker;

[jirihajek]

Just to clarify, I guess that the workerClass tweak isn't needed after you modify browserslist, or is it?

[theweaklink]

On my end it is still needed: I just tried again.

• with browserslist tweak only: building the app goes through however when serving it statically, I get the error m is not defined
• with both browserlist and workerClass tweaks: building and serving statically the app are both working well.

(I am using maplibre-gl@2.1.9)

[Deathis]

weblibregl doesn't have workerClass attribute. I'm using maplibre-gl@2.1.9+ react + typescript

[jirihajek]

Fyi, now I also need the workerClass trick in order to avoid the m is not defined error. I suppose some packages got updated in my enviroment, since originally the browserlist tweak was enough to get it working.

[apresmoi]

I'm using Gatsby 3.x. Adding the browserlist wasn't enough. I had to update maplibre-gl to the latest version and then change my implementation from:

import { Map } from "maplibre-gl";

to

//@ts-ignore
import maplibregl from "!maplibre-gl";
//@ts-ignore
import maplibreglWorker from "maplibre-gl/dist/maplibre-gl-csp-worker";
//@ts-ignore
maplibregl.workerClass = maplibreglWorker;

//Since I'm using typescript I have to import this one like this to be able to type the map variable
import { Map } from "maplibre-gl"; 

then you must initialize the map using:

const map: Map = new maplibregl.Map({ ... })

Thanks everyone !

[alanpilloud]

@apresmoi solutions worked for me too, using Gatsby 4.

Thanks a lot !

[VictorVelarde]

Thx a lot @apresmoi and @theweaklink
Your modifications worked also in my case (using import { Map } from 'react-map-gl';, in a create react app v4 project)

[HarelM]

This seems to have been solved. Closing.

[jirihajek]

I don't think that this issue should be closed yet. Not being able to be successfully compiled by Webpack is imho still an issue that we should try to find a real solution to. It's good that we have a workaround now, but it isn't a solution.

[HarelM]

I'm able to compile maplibre with angular that uses webpack.
The problem is not with this library, it might be webpack configuration or other stuff...

[rmjwilbur]

Was getting the following error using current versions: Uncaught ReferenceError: g is not defined on maps when deployed

The suggestion offered by @wipfli worked for me. Switched to a .browserslistrc containing:

`
# NOTE: Need to occasionally run "npm run browserslist" to update caniuselite

# NOTE: Was getting an error: Uncaught ReferenceError: g is not defined on maps when deployed
# Resolved by changing production settings as per #1011

[production]
defaults
not ie 11

[development]
last 1 chrome version
last 1 firefox version
last 1 safari version
`

I doubt switching to .browserslistrc made a difference but I took the opportunity to get this config out of my package.json

[lucaswoj]

Just in case anyone else runs into this issue, it is related to this upstream bug browserslist/browserslist#374, and the minimal fix is to add not android 4.4.3-4.4.4 to your browserslist settings.