Simple tool for extracting source code from sourcemaps.

sourcemap-extractor.js

/**
 * Simple tool for extracting source code from sourcemaps.
 * Requires axios for automatic fetching.
 * Puts extracted files in ./<sourcemap_file_name>_extracted/
 * Puts files from `../` (for example, webpack puts there node_modules) dir to _extracted/__/,
 * and files from `./` to _extracted/
 *
 * (c) teidesu 2019. Licensed under GPLv3.
 */

const fs = require('fs')
const { promisify } = require('util')
const readline = require('readline')
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
})
const path = require('path')
const readFile = promisify(fs.readFile)
const writeFile = promisify(fs.writeFile)
const mkdir = (path, options) => new Promise((resolve, reject) => {
    fs.mkdir(path, options, (err) => {
        if (err && err.code !== 'EEXIST') {
            reject(err)
        } else {
            resolve()
        }
    })
})
const mkdirs = async (p) => {
    const sep = path.sep
    const stack = []
    for (let it of p.split(sep)) {
        stack.push(it)
        await mkdir(stack.join(sep))
    }
}

rl.question('URL or path to file > ', async (it) => {
    let content
    if (it.match(/^https?:\/\//i)) {
        console.log('[+] Fetching sourcemap')
        const axios = require('axios')
        const { data } = await axios.get(it)
        content = data
    } else {
        content = await readFile(it)
    }
    it = it.split('/').pop().split('?')[0] + '_extracted'
    try {
        if (typeof content !== 'object') {
            content = JSON.parse(content)
        }

        if (!content.sources || !content.sourcesContent || content.sources.length !== content.sourcesContent.length) {
            throw 1
        }
    } catch (e) {
        console.error('[!] Sourcemap is either invalid or does not contain source code')
        console.log(e)
        process.exit(1)
        return
    }

    for (let i = 0; i < content.sources.length; i++) {
        let fname = content.sources[i].replace(/\.\./g, '__').replace(/[:*?'"<>|&]/gi, '')
        process.stdout.write('[~] ' + fname + '\r')
        await mkdirs(path.join(it, path.dirname(fname)))
        await writeFile(path.join(it, fname), content.sourcesContent[i])
    }

    console.log('\n[v] Finished!')
    process.exit(0)
})