Source maps not working?

🐛 bug report

I’m trying to move my application from next.js & webpack over to using parcel.

Everything seems to be working except there’s 1 random new error that wasn’t happening on next.js but is happening with the parcel & it’s breaking my application.

uncaught at  at  
 at  
TypeError: (0 , n.default) is not a function
    at http://localhost:3000/src.3248ba16.js:1280:1722
    at http://localhost:3000/src.3248ba16.js:1280:1415
    at Object.next (http://localhost:3000/src.3248ba16.js:1280:1520)
    at K (http://localhost:3000/src.3248ba16.js:1218:4337)
    at E (http://localhost:3000/src.3248ba16.js:1218:4062)
    at F (http://localhost:3000/src.3248ba16.js:1218:7973)
    at P (http://localhost:3000/src.3248ba16.js:1218:6802)
    at http://localhost:3000/src.3248ba16.js:1218:8536
    at Array.forEach (<anonymous>)
    at W (http://localhost:3000/src.3248ba16.js:1218:8509)

The actual error totally makes sense. It seems like switching to Parcel has somehow screwed up an import 🤔?

But ALL the stack traces are minified code with no source maps… Making this extremely difficult to debug.

🎛 Configuration (.babelrc, package.json, cli command)

.babelrc

{
    "presets": ["@babel/preset-env", "@babel/preset-react"],
    "plugins": [
        ["@babel/plugin-proposal-class-properties", { "loose": true }],
        "styled-components",
        [
            "module-resolver",
            {
                "root": ["."],
                "alias": {
                    "common": "./src/common",
                    "components": "./src/components",
                    "pages": "./pages",
                    "static": "./static",
                    "theme": "./src/theme",
                    "redash": "./redash"
                }
            }
        ]
    ]
}

Parcel command I’m running:

export NODE_OPTIONS=--max-old-space-size=8192; parcel ./src/index.html --port 3000

🤔 Expected Behavior

Should generate all source maps in development mode, and show a useful stacktrace.

😯 Current Behavior

No source maps are available

💁 Possible Solution

No clue.

🌍 Your Environment

“parcel-bundler”: “^1.12.4”

[philtune]

Hi, I’m having the same issue. There is no setting to tell the compiled JS files where to look for the source map. /js/scripts.min.js just has //# sourceMappingURL=/scripts.min.js.map, but it needs to be /js/scripts.min.js.map or else needs to just be relative (no leading slash, which makes the most sense) //# sourceMappingURL=scripts.min.js.map

[brandon-okert-hs]

@jessabyrne https://parceljs.org/cli.html#set-the-public-url-to-serve-on eg: parcel build ./web/assets/js/main.js --out-dir ./build/assets --public-url /assets

Assuming you host your assets on eg yoursite:port/assets/main.js

Not sure if updating the docs here is the right place to add some clarification.