Url.prototype.parse = function()

in MultiRegion/2_UI/src/assets/js/aws/aws-cognito-sdk.js [15406:15581]
150 lines of code
58 McCabe index (conditional complexity)

Url.prototype.parse = function(url, parseQueryString, slashesDenoteHost) {
  if (!isString(url)) {
    throw new TypeError("Parameter 'url' must be a string, not " + typeof url);
  }

  var rest = url;

  rest = rest.trim();

  var proto = protocolPattern.exec(rest);
  if (proto) {
    proto = proto[0];
    var lowerProto = proto.toLowerCase();
    this.protocol = lowerProto;
    rest = rest.substr(proto.length);
  }

  if (slashesDenoteHost || proto || rest.match(/^\/\/[^@\/]+@[^@\/]+/)) {
    var slashes = rest.substr(0, 2) === '//';
    if (slashes && !(proto && hostlessProtocol[proto])) {
      rest = rest.substr(2);
      this.slashes = true;
    }
  }

  if (!hostlessProtocol[proto] &&
      (slashes || (proto && !slashedProtocol[proto]))) {



    var hostEnd = -1;
    for (var i = 0; i < hostEndingChars.length; i++) {
      var hec = rest.indexOf(hostEndingChars[i]);
      if (hec !== -1 && (hostEnd === -1 || hec < hostEnd))
        hostEnd = hec;
    }

    var auth, atSign;
    if (hostEnd === -1) {
      atSign = rest.lastIndexOf('@');
    } else {
      atSign = rest.lastIndexOf('@', hostEnd);
    }

    if (atSign !== -1) {
      auth = rest.slice(0, atSign);
      rest = rest.slice(atSign + 1);
      this.auth = decodeURIComponent(auth);
    }

    hostEnd = -1;
    for (var i = 0; i < nonHostChars.length; i++) {
      var hec = rest.indexOf(nonHostChars[i]);
      if (hec !== -1 && (hostEnd === -1 || hec < hostEnd))
        hostEnd = hec;
    }
    if (hostEnd === -1)
      hostEnd = rest.length;

    this.host = rest.slice(0, hostEnd);
    rest = rest.slice(hostEnd);

    this.parseHost();

    this.hostname = this.hostname || '';

    var ipv6Hostname = this.hostname[0] === '[' &&
        this.hostname[this.hostname.length - 1] === ']';

    if (!ipv6Hostname) {
      var hostparts = this.hostname.split(/\./);
      for (var i = 0, l = hostparts.length; i < l; i++) {
        var part = hostparts[i];
        if (!part) continue;
        if (!part.match(hostnamePartPattern)) {
          var newpart = '';
          for (var j = 0, k = part.length; j < k; j++) {
            if (part.charCodeAt(j) > 127) {
              newpart += 'x';
            } else {
              newpart += part[j];
            }
          }
          if (!newpart.match(hostnamePartPattern)) {
            var validParts = hostparts.slice(0, i);
            var notHost = hostparts.slice(i + 1);
            var bit = part.match(hostnamePartStart);
            if (bit) {
              validParts.push(bit[1]);
              notHost.unshift(bit[2]);
            }
            if (notHost.length) {
              rest = '/' + notHost.join('.') + rest;
            }
            this.hostname = validParts.join('.');
            break;
          }
        }
      }
    }

    if (this.hostname.length > hostnameMaxLen) {
      this.hostname = '';
    } else {
      this.hostname = this.hostname.toLowerCase();
    }

    if (!ipv6Hostname) {
      var domainArray = this.hostname.split('.');
      var newOut = [];
      for (var i = 0; i < domainArray.length; ++i) {
        var s = domainArray[i];
        newOut.push(s.match(/[^A-Za-z0-9_-]/) ?
            'xn--' + punycode.encode(s) : s);
      }
      this.hostname = newOut.join('.');
    }

    var p = this.port ? ':' + this.port : '';
    var h = this.hostname || '';
    this.host = h + p;
    this.href += this.host;

    if (ipv6Hostname) {
      this.hostname = this.hostname.substr(1, this.hostname.length - 2);
      if (rest[0] !== '/') {
        rest = '/' + rest;
      }
    }
  }

  if (!unsafeProtocol[lowerProto]) {

    for (var i = 0, l = autoEscape.length; i < l; i++) {
      var ae = autoEscape[i];
      var esc = encodeURIComponent(ae);
      if (esc === ae) {
        esc = escape(ae);
      }
      rest = rest.split(ae).join(esc);
    }
  }


  var hash = rest.indexOf('#');
  if (hash !== -1) {
    this.hash = rest.substr(hash);
    rest = rest.slice(0, hash);
  }
  var qm = rest.indexOf('?');
  if (qm !== -1) {
    this.search = rest.substr(qm);
    this.query = rest.substr(qm + 1);
    if (parseQueryString) {
      this.query = querystring.parse(this.query);
    }
    rest = rest.slice(0, qm);
  } else if (parseQueryString) {
    this.search = '';
    this.query = {};
  }
  if (rest) this.pathname = rest;
  if (slashedProtocol[lowerProto] &&
      this.hostname && !this.pathname) {
    this.pathname = '/';
  }

  if (this.pathname || this.search) {
    var p = this.pathname || '';
    var s = this.search || '';
    this.path = p + s;
  }

  this.href = this.format();
  return this;
};