index.js

'use strict';
/**
  Overly tolerant url parser
 */

var Url = module.exports = {
  PROTOCOL: '://',
  COLON: ':',
  AT: '@',
  SLASH: '/',
  parse: function (url) {
    // first parse auth/host/port
    var parsed = this._parse(url);

    // then handle path (quick & dirty way)
    ['host', 'hostname', 'port'].forEach(function (part) {
      if (strCount(parsed[part], this.SLASH) > 0) {
        var pair = parsed[part].split(this.SLASH);
        parsed[part] = pair.shift();
        parsed.path = this.SLASH + pair.join(this.SLASH);
      }
    }, this);

    return parsed;
  },
  _parse: function (url) {
    var parsed = {
      protocol: null, // string
      auth: null, // string
      hostname: null, // string
      host: null, // string
      port: null, // string
      href: url, // string
      path: null
    };

    // check protocol
    var protocolIdx = url.indexOf(this.PROTOCOL);
    if (protocolIdx !== -1) {
      parsed.protocol = url.substring(0, protocolIdx + 1);
      protocolIdx += this.PROTOCOL.length;
      // remove the protocol part from the url
      url = url.substring(protocolIdx);
    }

    var atCount = strCount(url, this.AT);
    var colonCount = strCount(url, this.COLON);
    var atIsPresent = atCount > 0;
    var colonIsPresent = colonCount > 0;

    if (!atIsPresent && !colonIsPresent) {
      parsed.host = url;
      parsed.hostname = url;
      // parse is done, there are no port and auth
      return parsed;
    }

    if (colonCount === 1 && !atIsPresent) { // it can only be the port number
      extractPortAndHostnameFromHost(parsed, url);
      return parsed;
    }

    var parts = url.split(this.AT);
    var host = parts.pop();
    extractPortAndHostnameFromHost(parsed, host);
    parsed.auth = parts.join(this.AT);
    return parsed;
  }
};


function strCount(str, substr) {
  if (str === null || substr === null) {
    return 0;
  }
  str = String(str);
  substr = String(substr);

  var count = 0,
    pos = 0,
    length = substr.length;

  while (true) {
    pos = str.indexOf(substr, pos);
    if (pos === -1) {
      break;
    }
    count++;
    pos += length;
  }

  return count;
}

function extractPortAndHostnameFromHost(parsed, host) {
  var portIdx = host.indexOf(Url.COLON);
  parsed.host = host;

  if (portIdx === -1) {
    parsed.hostname = host;
    // no colon is present inside host
    return;
  }
  parsed.port = host.substring(portIdx + Url.COLON.length);
  parsed.hostname = host.substring(0, portIdx);
}