index.mjs

import * as fsPromises from 'node:fs/promises'
import * as fs from 'node:fs'
import * as path from 'path'
import { SourceMapConsumer } from 'source-map'
import * as archiver from 'archiver'

async function readHarFile(fileName) {
    const harFileContent = await fsPromises.readFile(fileName, 'utf8')
    const harFile = JSON.parse(harFileContent)
    return harFile
}

const harFile = await readHarFile(process.argv[2])
let filesWithSourceMap = harFile.log.entries
    .filter(entry => entry.response.content.text?.includes('//# sourceMappingURL='));

const output = fs.createWriteStream('/tmp/output.zip');
const archive = archiver.default('zip')
archive.pipe(output)

const knownFiles = new Set();
for (const entryIdx in filesWithSourceMap) {
    const entry = filesWithSourceMap[entryIdx]
    console.log(entryIdx, '/', filesWithSourceMap.length)
    // create a file to stream archive data to.
    const originalUrl = entry.request.url;
    const sourceMapPath = entry.response.content.text.split('//# sourceMappingURL=').at(-1);
    const u = new URL(originalUrl)
    u.pathname = path.resolve(u.pathname, '../' + sourceMapPath)

    console.log('fetching', u)
    const response = await fetch(u)
    const text = await response.text()



    const result = await SourceMapConsumer.with(text, null, async function (consumer) {
        return consumer.sources
            .filter(source => !source.startsWith('/node_modules'))
            .map(source => {
                return [source, consumer.sourceContentFor(source)]
            })
    })
    result.forEach(([path, content]) => {
        if (knownFiles.has(path)) {
            console.log('I already have seen', path)
        }
        knownFiles.add(path)
        try {
            // it can be undefined?
            if (content) {
                archive.append(content, { name: path })
            } else {
                console.error('warning: content is undefined for path', path)
            }
        } catch (e) {
            console.error('error', e)
        }
    })
}

await archive.finalize()

package.json

{
  "name": "har-to-sourcemap",
  "packageManager": "yarn@4.2.2",
  "private": true,
  "dependencies": {
    "archiver": "7.0.1",
    "source-map": "0.7.4"
  },
  "devDependencies": {
    "@types/archiver": "6.0.2"
  }
}