source-un-map

index.js

var http = require("http");
var https = require("https");
var { SourceMapConsumer } = require("source-map");
var fs = require("fs").promises;
var path = require("path");

var fetch = function(address) {
  return new Promise(function(ok, fail) {
    var parsed = new URL(address);
    var remote = parsed.protocol == "http:" ? http : https;
    var { host, pathname, search } = parsed;
    var p = remote.get({
      host,
      path: pathname + search,
      headers: {
        "User-Agent": "Radio"
      }
    }, function(proxied) {
      if (proxied.statusCode > 300 && proxied.headers.location) {
        return fetch(proxied.headers.location, output);
      }
      var body = "";
      proxied.on("data", chunk => body += chunk.toString("utf-8"));
      proxied.on("end", () => ok(body));
    });
    p.on("error", fail);
  });
}

var main = async function(input, output = "./output") {
  var js = await fetch(input);
  var smFile = js.match(/^\/\/# sourceMappingURL\s*=\s*(.+)$/m)[1];
  var smURL = new URL(smFile, input);
  var map = await fetch(smURL.toString());
  var consumer = await new SourceMapConsumer(map);
  output = path.resolve(output);
  for (var source of consumer.sources) {
    if (source.match(/node_modules/)) continue;
    var file = path.join(output, source);
    var contents = consumer.sourceContentFor(source);
    await fs.mkdir(path.dirname(file), { recursive: true });
    await fs.writeFile(file, contents);
  }
  consumer.destroy();
}

var args = process.argv.slice(2);
var [input, output] = args;
main(input, output);