Unable to parse webpack source URLs, how to work around around?

[lancejpollard]

It looks like it's failing right here:

source-map/lib/util.js

Line 181 in 60adcb0

const url = new URL(input, base);

I have this code for parsing the string sourcemap from a JS file, but it's not working:

const CACHE: Record<string, SourceMapConsumer> = {}

async function loadFile(
  line: string,
): Promise<SourceMapConsumer | void> {
  const link = CACHE[`${line}`]
  if (link) {
    return link
  }

  const res = await fetch(line)
  const text = await res.text()
  const last = text.trim().split('\n').pop() ?? ''
  console.log(text)
  console.log(last)
  if (
    last.match(
      /(\/\/# sourceMappingURL=data:application\/json;charset=utf-8;base64,)/,
    )
  ) {
    console.log(last.slice(RegExp.$1.length))
    const json = JSON.parse(
      atob(last.slice(RegExp.$1.length)),
    ) as RawSourceMap
    json.sources.forEach((source, i) => {
      json.sources[i] = source.replace(/^webpack:\/\//g, 'http://')
    })
    console.log(json)

    const sm = await new SourceMapConsumer(json)
    CACHE[`${line}`] = sm
    return sm
  }
}

async function readFileLocation(
  file: string,
  line: number,
  rise: number,
): Promise<[string, number | undefined, number | undefined]> {
  const link = await loadFile(file)

  const trace = {
    column: rise,
    filename: file,
    line: line,
  }

  if (link) {
    const token = link.originalPositionFor(trace)
    if (token.source) {
      return [
        token.source,
        token.line == null ? undefined : token.line,
        token.column == null ? undefined : token.column,
      ]
    } else {
      return [file, line, rise]
    }
  } else {
    return [file, line, rise]
  }
}

export async function testSourceMaps(error: Error): Promise<string> {
  const stack = getFileLineColumn(error.stack?.split('\n') ?? [])
  const list: Array<string> = []

  for (const data of stack) {
    const [file, line, column] = await readFileLocation(
      data.file,
      data.line ?? 0,
      data.column ?? 0,
    )

    console.log(file, line, column)
  }
}

As you can see in the example, I tried to replace webpack:// with http:// but it didn't seem to help:

json.sources[i] = source.replace(/^webpack:\/\//g, 'http://')

How do I get this working, any suggestions? The error I'm getting is:

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'decode')
    at new URLStateMachine (url-state-machine.js:546:1)
    at module.exports.basicURLParse (url-state-machine.js:1264:1)
    at new URLImpl (URL-impl.js:13:1)
    at Object.setup (URL.js:317:1)
    at new URL (URL.js:26:1)
    at util.js:179:1
    at Object.computeSourceURL (util.js:431:1)
    at source-map-consumer.js:207:1
    at Array.map (<anonymous>)
    at source-map-consumer.js:206:1

The JSON looks liek this when I parse the sourcemap in this fashion:

Any help would be greatly appreciated. Thank you.

[martypdx]

@lancejpollard I would test the URL creation in isolation. That seems to be your probably moreso any sourcemap issue. Given the stack track, it looks like this is the URL implementation being used.

If you can make sure your url string works in the constructor, then you just need to validate your replace algorithm produces the exact right string.

Also, be aware that URL will remove the extraneous dot file path: http://task/./node_modules becomes http://task/node_modules.

[jkrems]

URL shouldn't touch the path for unknown schemes (like webpack://) which also means it's somewhat important to not change the scheme. Example:

> new URL('webpack://task/./node_modules/foo/bar.js').href
'webpack://task/./node_modules/foo/bar.js'
> new URL('https://task/./node_modules/foo/bar.js').href
'https://task/node_modules/foo/bar.js'

[martypdx]

Ah right, special resolution for privileged schemas