browser-es-module-loader/dist/browser-es-module-loader.js

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
  typeof define === 'function' && define.amd ? define(factory) :
  (global.BrowserESModuleLoader = factory());
}(this, (function () { 'use strict';

/*
 * Environment
 */
var isBrowser = typeof window !== 'undefined' && typeof document !== 'undefined';
var isNode = typeof process !== 'undefined' && process.versions && process.versions.node;
var isWindows = typeof process !== 'undefined' && typeof process.platform === 'string' && process.platform.match(/^win/);

var envGlobal = typeof self !== 'undefined' ? self : global;
/*
 * Simple Symbol() shim
 */
var hasSymbol = typeof Symbol !== 'undefined';
function createSymbol (name) {
  return hasSymbol ? Symbol() : '@@' + name;
}

/*
 * Environment baseURI
 */
var baseURI;

// environent baseURI detection
if (typeof document != 'undefined' && document.getElementsByTagName) {
  baseURI = document.baseURI;

  if (!baseURI) {
    var bases = document.getElementsByTagName('base');
    baseURI = bases[0] && bases[0].href || window.location.href;
  }
}
else if (typeof location != 'undefined') {
  baseURI = location.href;
}

// sanitize out the hash and querystring
if (baseURI) {
  baseURI = baseURI.split('#')[0].split('?')[0];
  baseURI = baseURI.substr(0, baseURI.lastIndexOf('/') + 1);
}
else if (typeof process != 'undefined' && process.cwd) {
  baseURI = 'file://' + (isWindows ? '/' : '') + process.cwd();
  if (isWindows)
    baseURI = baseURI.replace(/\\/g, '/');
}
else {
  throw new TypeError('No environment baseURI');
}

// ensure baseURI has trailing "/"
if (baseURI[baseURI.length - 1] !== '/')
  baseURI += '/';

/*
 * LoaderError with chaining for loader stacks
 */
var errArgs = new Error(0, '_').fileName == '_';
function LoaderError__Check_error_message_for_loader_stack (childErr, newMessage) {
  // Convert file:/// URLs to paths in Node
  if (!isBrowser)
    newMessage = newMessage.replace(isWindows ? /file:\/\/\//g : /file:\/\//g, '');

  var message = (childErr.message || childErr) + '\n  ' + newMessage;

  var err;
  if (errArgs && childErr.fileName)
    err = new Error(message, childErr.fileName, childErr.lineNumber);
  else
    err = new Error(message);


  var stack = childErr.originalErr ? childErr.originalErr.stack : childErr.stack;

  if (isNode)
    // node doesn't show the message otherwise
    err.stack = message + '\n  ' + stack;
  else
    err.stack = stack;

  err.originalErr = childErr.originalErr || childErr;

  return err;
}

var resolvedPromise = Promise.resolve();

/*
 * Simple Array values shim
 */
function arrayValues (arr) {
  if (arr.values)
    return arr.values();

  if (typeof Symbol === 'undefined' || !Symbol.iterator)
    throw new Error('Symbol.iterator not supported in this browser');

  var iterable = {};
  iterable[Symbol.iterator] = function () {
    var keys = Object.keys(arr);
    var keyIndex = 0;
    return {
      next: function () {
        if (keyIndex < keys.length)
          return {
            value: arr[keys[keyIndex++]],
            done: false
          };
        else
          return {
            value: undefined,
            done: true
          };
      }
    };
  };
  return iterable;
}

/*
 * 3. Reflect.Loader
 *
 * We skip the entire native internal pipeline, just providing the bare API
 */
// 3.1.1
function Loader () {
  this.registry = new Registry();
}
// 3.3.1
Loader.prototype.constructor = Loader;

function ensureInstantiated (module) {
  if (!(module instanceof ModuleNamespace))
    throw new TypeError('Module instantiation did not return a valid namespace object.');
  return module;
}

// 3.3.2
Loader.prototype.import = function (key, parent) {
  if (typeof key !== 'string')
    throw new TypeError('Loader import method must be passed a module key string');
  // custom resolveInstantiate combined hook for better perf
  var loader = this;
  return resolvedPromise
  .then(function () {
    return loader[RESOLVE_INSTANTIATE](key, parent);
  })
  .then(ensureInstantiated)
  //.then(Module.evaluate)
  .catch(function (err) {
    throw LoaderError__Check_error_message_for_loader_stack(err, 'Loading ' + key + (parent ? ' from ' + parent : ''));
  });
};
// 3.3.3
var RESOLVE = Loader.resolve = createSymbol('resolve');

/*
 * Combined resolve / instantiate hook
 *
 * Not in current reduced spec, but necessary to separate RESOLVE from RESOLVE + INSTANTIATE as described
 * in the spec notes of this repo to ensure that loader.resolve doesn't instantiate when not wanted.
 *
 * We implement RESOLVE_INSTANTIATE as a single hook instead of a separate INSTANTIATE in order to avoid
 * the need for double registry lookups as a performance optimization.
 */
var RESOLVE_INSTANTIATE = Loader.resolveInstantiate = createSymbol('resolveInstantiate');

// default resolveInstantiate is just to call resolve and then get from the registry
// this provides compatibility for the resolveInstantiate optimization
Loader.prototype[RESOLVE_INSTANTIATE] = function (key, parent) {
  var loader = this;
  return loader.resolve(key, parent)
  .then(function (resolved) {
    return loader.registry.get(resolved);
  });
};

function ensureResolution (resolvedKey) {
  if (resolvedKey === undefined)
    throw new RangeError('No resolution found.');
  return resolvedKey;
}

Loader.prototype.resolve = function (key, parent) {
  var loader = this;
  return resolvedPromise
  .then(function() {
    return loader[RESOLVE](key, parent);
  })
  .then(ensureResolution)
  .catch(function (err) {
    throw LoaderError__Check_error_message_for_loader_stack(err, 'Resolving ' + key + (parent ? ' to ' + parent : ''));
  });
};

// 3.3.4 (import without evaluate)
// this is not documented because the use of deferred evaluation as in Module.evaluate is not
// documented, as it is not considered a stable feature to be encouraged
// Loader.prototype.load may well be deprecated if this stays disabled
/* Loader.prototype.load = function (key, parent) {
  return Promise.resolve(this[RESOLVE_INSTANTIATE](key, parent || this.key))
  .catch(function (err) {
    throw addToError(err, 'Loading ' + key + (parent ? ' from ' + parent : ''));
  });
}; */

/*
 * 4. Registry
 *
 * Instead of structuring through a Map, just use a dictionary object
 * We throw for construction attempts so this doesn't affect the public API
 *
 * Registry has been adjusted to use Namespace objects over ModuleStatus objects
 * as part of simplifying loader API implementation
 */
var iteratorSupport = typeof Symbol !== 'undefined' && Symbol.iterator;
var REGISTRY = createSymbol('registry');
function Registry() {
  this[REGISTRY] = {};
  this._registry = REGISTRY;
}
// 4.4.1
if (iteratorSupport) {
  // 4.4.2
  Registry.prototype[Symbol.iterator] = function () {
    return this.entries()[Symbol.iterator]();
  };

  // 4.4.3
  Registry.prototype.entries = function () {
    var registry = this[REGISTRY];
    return arrayValues(Object.keys(registry).map(function (key) {
      return [key, registry[key]];
    }));
  };
}

// 4.4.4
Registry.prototype.keys = function () {
  return arrayValues(Object.keys(this[REGISTRY]));
};
// 4.4.5
Registry.prototype.values = function () {
  var registry = this[REGISTRY];
  return arrayValues(Object.keys(registry).map(function (key) {
    return registry[key];
  }));
};
// 4.4.6
Registry.prototype.get = function (key) {
  return this[REGISTRY][key];
};
// 4.4.7
Registry.prototype.set = function (key, namespace) {
  if (!(namespace instanceof ModuleNamespace))
    throw new Error('Registry must be set with an instance of Module Namespace');
  this[REGISTRY][key] = namespace;
  return this;
};
// 4.4.8
Registry.prototype.has = function (key) {
  return Object.hasOwnProperty.call(this[REGISTRY], key);
};
// 4.4.9
Registry.prototype.delete = function (key) {
  if (Object.hasOwnProperty.call(this[REGISTRY], key)) {
    delete this[REGISTRY][key];
    return true;
  }
  return false;
};

/*
 * Simple ModuleNamespace Exotic object based on a baseObject
 * We export this for allowing a fast-path for module namespace creation over Module descriptors
 */
// var EVALUATE = createSymbol('evaluate');
var BASE_OBJECT = createSymbol('baseObject');

// 8.3.1 Reflect.Module
/*
 * Best-effort simplified non-spec implementation based on
 * a baseObject referenced via getters.
 *
 * Allows:
 *
 *   loader.registry.set('x', new Module({ default: 'x' }));
 *
 * Optional evaluation function provides experimental Module.evaluate
 * support for non-executed modules in registry.
 */
function ModuleNamespace (baseObject/*, evaluate*/) {
  Object.defineProperty(this, BASE_OBJECT, {
    value: baseObject
  });

  // evaluate defers namespace population
  /* if (evaluate) {
    Object.defineProperty(this, EVALUATE, {
      value: evaluate,
      configurable: true,
      writable: true
    });
  }
  else { */
    Object.keys(baseObject).forEach(extendNamespace, this);
  //}
};
// 8.4.2
ModuleNamespace.prototype = Object.create(null);

if (typeof Symbol !== 'undefined' && Symbol.toStringTag)
  Object.defineProperty(ModuleNamespace.prototype, Symbol.toStringTag, {
    value: 'Module'
  });

function extendNamespace (key) {
  Object.defineProperty(this, key, {
    enumerable: true,
    get: function () {
      return this[BASE_OBJECT][key];
    }
  });
}

/* function doEvaluate (evaluate, context) {
  try {
    evaluate.call(context);
  }
  catch (e) {
    return e;
  }
}

// 8.4.1 Module.evaluate... not documented or used because this is potentially unstable
Module.evaluate = function (ns) {
  var evaluate = ns[EVALUATE];
  if (evaluate) {
    ns[EVALUATE] = undefined;
    var err = doEvaluate(evaluate);
    if (err) {
      // cache the error
      ns[EVALUATE] = function () {
        throw err;
      };
      throw err;
    }
    Object.keys(ns[BASE_OBJECT]).forEach(extendNamespace, ns);
  }
  // make chainable
  return ns;
}; */

/*
 * Optimized URL normalization assuming a syntax-valid URL parent
 */
function throwResolveError () {
  throw new RangeError('Unable to resolve "' + relUrl + '" to ' + parentUrl);
}
function resolveIfNotPlain (relUrl, parentUrl) {
  var parentProtocol = parentUrl && parentUrl.substr(0, parentUrl.indexOf(':') + 1);

  var firstChar = relUrl[0];
  var secondChar = relUrl[1];

  // protocol-relative
  if (firstChar === '/' && secondChar === '/') {
    if (!parentProtocol)
      throwResolveError(relUrl, parentUrl);
    return parentProtocol + relUrl;
  }
  // relative-url
  else if (firstChar === '.' && (secondChar === '/' || secondChar === '.' && (relUrl[2] === '/' || relUrl.length === 2) || relUrl.length === 1)
      || firstChar === '/') {
    var parentIsPlain = !parentProtocol || parentUrl[parentProtocol.length] !== '/';

    // read pathname from parent if a URL
    // pathname taken to be part after leading "/"
    var pathname;
    if (parentIsPlain) {
      // resolving to a plain parent -> skip standard URL prefix, and treat entire parent as pathname
      if (parentUrl === undefined)
        throwResolveError(relUrl, parentUrl);
      pathname = parentUrl;
    }
    else if (parentUrl[parentProtocol.length + 1] === '/') {
      // resolving to a :// so we need to read out the auth and host
      if (parentProtocol !== 'file:') {
        pathname = parentUrl.substr(parentProtocol.length + 2);
        pathname = pathname.substr(pathname.indexOf('/') + 1);
      }
      else {
        pathname = parentUrl.substr(8);
      }
    }
    else {
      // resolving to :/ so pathname is the /... part
      pathname = parentUrl.substr(parentProtocol.length + 1);
    }

    if (firstChar === '/') {
      if (parentIsPlain)
        throwResolveError(relUrl, parentUrl);
      else
        return parentUrl.substr(0, parentUrl.length - pathname.length - 1) + relUrl;
    }

    // join together and split for removal of .. and . segments
    // looping the string instead of anything fancy for perf reasons
    // '../../../../../z' resolved to 'x/y' is just 'z' regardless of parentIsPlain
    var segmented = pathname.substr(0, pathname.lastIndexOf('/') + 1) + relUrl;

    var output = [];
    var segmentIndex = undefined;

    for (var i = 0; i < segmented.length; i++) {
      // busy reading a segment - only terminate on '/'
      if (segmentIndex !== undefined) {
        if (segmented[i] === '/') {
          output.push(segmented.substr(segmentIndex, i - segmentIndex + 1));
          segmentIndex = undefined;
        }
        continue;
      }

      // new segment - check if it is relative
      if (segmented[i] === '.') {
        // ../ segment
        if (segmented[i + 1] === '.' && (segmented[i + 2] === '/' || i === segmented.length - 2)) {
          output.pop();
          i += 2;
        }
        // ./ segment
        else if (segmented[i + 1] === '/' || i === segmented.length - 1) {
          i += 1;
        }
        else {
          // the start of a new segment as below
          segmentIndex = i;
          continue;
        }

        // this is the plain URI backtracking error (../, package:x -> error)
        if (parentIsPlain && output.length === 0)
          throwResolveError(relUrl, parentUrl);

        // trailing . or .. segment
        if (i === segmented.length)
          output.push('');
        continue;
      }

      // it is the start of a new segment
      segmentIndex = i;
    }
    // finish reading out the last segment
    if (segmentIndex !== undefined)
      output.push(segmented.substr(segmentIndex, segmented.length - segmentIndex));

    return parentUrl.substr(0, parentUrl.length - pathname.length) + output.join('');
  }

  // sanitizes and verifies (by returning undefined if not a valid URL-like form)
  // Windows filepath compatibility is an added convenience here
  var protocolIndex = relUrl.indexOf(':');
  if (protocolIndex !== -1) {
    if (isNode) {
      // C:\x becomes file:///c:/x (we don't support C|\x)
      if (relUrl[1] === ':' && relUrl[2] === '\\' && relUrl[0].match(/[a-z]/i))
        return 'file:///' + relUrl.replace(/\\/g, '/');
    }
    return relUrl;
  }
}

/*
 * Register Loader
 *
 * Builds directly on top of loader polyfill to provide:
 * - loader.register support
 * - hookable higher-level resolve
 * - instantiate hook returning a ModuleNamespace or undefined for es module loading
 * - loader error behaviour as in HTML and loader specs, clearing failed modules from registration cache synchronously
 * - build tracing support by providing a .trace=true and .loads object format
 */

var REGISTER_INTERNAL = createSymbol('register-internal');

function RegisterLoader () {
  Loader.call(this);

  this[REGISTER_INTERNAL] = {
    // last anonymous System.register call
    lastRegister: undefined,
    // in-flight es module load records
    records: {}
  }

  // tracing
  this.trace = false;
}

RegisterLoader.prototype = Object.create(Loader.prototype);
RegisterLoader.prototype.constructor = RegisterLoader;

var INSTANTIATE = RegisterLoader.instantiate = createSymbol('instantiate');

// default normalize is the WhatWG style normalizer
RegisterLoader.prototype[RegisterLoader.resolve = Loader.resolve] = function (key, parentKey) {
  return resolveIfNotPlain(key, parentKey || baseURI);
};

RegisterLoader.prototype[INSTANTIATE] = function (key, processAnonRegister) {};

// once evaluated, the linkRecord is set to undefined leaving just the other load record properties
// this allows tracking new binding listeners for es modules through importerSetters
// for dynamic modules, the load record is removed entirely.
function createLoadRecord (state, key, registration) {
  return state.records[key] = {
    key: key,

    // defined System.register cache
    registration: registration,

    // module namespace object
    module: undefined,

    // es-only
    // this sticks around so new module loads can listen to binding changes
    // for already-loaded modules by adding themselves to their importerSetters
    importerSetters: undefined,

    // in-flight linking record
    linkRecord: {
      // promise for instantiated
      instantiatePromise: undefined,
      dependencies: undefined,
      execute: undefined,
      executingRequire: false,

      // underlying module object bindings
      moduleObj: undefined,

      // es only, also indicates if es or not
      setters: undefined,

      // promise for instantiated dependencies (dependencyInstantiations populated)
      depsInstantiatePromise: undefined,
      // will be the array of dependency load record or a module namespace
      dependencyInstantiations: undefined,

      // indicates if the load and all its dependencies are instantiated and linked
      // but not yet executed
      // mostly just a performance shortpath to avoid rechecking the promises above
      linked: false,

      error: undefined
      // NB optimization and way of ensuring module objects in setters
      // indicates setters which should run pre-execution of that dependency
      // setters is then just for completely executed module objects
      // alternatively we just pass the partially filled module objects as
      // arguments into the execute function
      // hoisted: undefined
    }
  };
}

RegisterLoader.prototype[Loader.resolveInstantiate] = function (key, parentKey) {
  var loader = this;
  var state = this[REGISTER_INTERNAL];
  var registry = loader.registry[loader.registry._registry];

  return resolveInstantiate(loader, key, parentKey, registry, state)
  .then(function (instantiated) {
    if (instantiated instanceof ModuleNamespace)
      return instantiated;

    // if already beaten to linked, return
    if (instantiated.module)
      return instantiated.module;

    // resolveInstantiate always returns a load record with a link record and no module value
    if (instantiated.linkRecord.linked)
      return ensureEvaluate(loader, instantiated, instantiated.linkRecord, registry, state, undefined);

    return instantiateDeps(loader, instantiated, instantiated.linkRecord, registry, state, [instantiated])
    .then(function () {
      return ensureEvaluate(loader, instantiated, instantiated.linkRecord, registry, state, undefined);
    })
    .catch(function (err) {
      clearLoadErrors(loader, instantiated);
      throw err;
    });
  });
};

function resolveInstantiate (loader, key, parentKey, registry, state) {
  // normalization shortpath for already-normalized key
  // could add a plain name filter, but doesn't yet seem necessary for perf
  var module = registry[key];
  if (module)
    return Promise.resolve(module);

  var load = state.records[key];

  // already linked but not in main registry is ignored
  if (load && !load.module)
    return instantiate(loader, load, load.linkRecord, registry, state);

  return loader.resolve(key, parentKey)
  .then(function (resolvedKey) {
    // main loader registry always takes preference
    module = registry[resolvedKey];
    if (module)
      return module;

    load = state.records[resolvedKey];

    // already has a module value but not already in the registry (load.module)
    // means it was removed by registry.delete, so we should
    // disgard the current load record creating a new one over it
    // but keep any existing registration
    if (!load || load.module)
      load = createLoadRecord(state, resolvedKey, load && load.registration);

    var link = load.linkRecord;
    if (!link)
      return load;

    return instantiate(loader, load, link, registry, state);
  });
}

function createProcessAnonRegister (loader, load, state) {
  return function () {
    var lastRegister = state.lastRegister;

    if (!lastRegister)
      return !!load.registration;

    state.lastRegister = undefined;
    load.registration = lastRegister;

    return true;
  };
}

function instantiate (loader, load, link, registry, state) {
  return link.instantiatePromise || (link.instantiatePromise =
  // if there is already an existing registration, skip running instantiate
  (load.registration ? Promise.resolve() : Promise.resolve().then(function () {
    state.lastRegister = undefined;
    return loader[INSTANTIATE](load.key, loader[INSTANTIATE].length > 1 && createProcessAnonRegister(loader, load, state));
  }))
  .then(function (instantiation) {
    // direct module return from instantiate -> we're done
    if (instantiation !== undefined) {
      if (!(instantiation instanceof ModuleNamespace))
        throw new TypeError('Instantiate did not return a valid Module object.');

      delete state.records[load.key];
      if (loader.trace)
        traceLoad(loader, load, link);
      return registry[load.key] = instantiation;
    }

    // run the cached loader.register declaration if there is one
    var registration = load.registration;
    // clear to allow new registrations for future loads (combined with registry delete)
    load.registration = undefined;
    if (!registration)
      throw new TypeError('Module instantiation did not call an anonymous or correctly named System.register.');

    link.dependencies = registration[0];

    load.importerSetters = [];

    link.moduleObj = {};

    // process System.registerDynamic declaration
    if (registration[2]) {
      link.moduleObj.default = {};
      link.moduleObj.__useDefault = true;
      link.executingRequire = registration[1];
      link.execute = registration[2];
    }

    // process System.register declaration
    else {
      registerDeclarative(loader, load, link, registration[1]);
    }

    // shortpath to instantiateDeps
    if (!link.dependencies.length) {
      link.linked = true;
      if (loader.trace)
        traceLoad(loader, load, link);
    }

    return load;
  })
  .catch(function (err) {
    throw link.error = LoaderError__Check_error_message_for_loader_stack(err, 'Instantiating ' + load.key);
  }));
}

// like resolveInstantiate, but returning load records for linking
function resolveInstantiateDep (loader, key, parentKey, registry, state, traceDepMap) {
  // normalization shortpaths for already-normalized key
  // DISABLED to prioritise consistent resolver calls
  // could add a plain name filter, but doesn't yet seem necessary for perf
  /* var load = state.records[key];
  var module = registry[key];

  if (module) {
    if (traceDepMap)
      traceDepMap[key] = key;

    // registry authority check in case module was deleted or replaced in main registry
    if (load && load.module && load.module === module)
      return load;
    else
      return module;
  }

  // already linked but not in main registry is ignored
  if (load && !load.module) {
    if (traceDepMap)
      traceDepMap[key] = key;
    return instantiate(loader, load, load.linkRecord, registry, state);
  } */
  return loader.resolve(key, parentKey)
  .then(function (resolvedKey) {
    if (traceDepMap)
      traceDepMap[key] = key;

    // normalization shortpaths for already-normalized key
    var load = state.records[resolvedKey];
    var module = registry[resolvedKey];

    // main loader registry always takes preference
    if (module && (!load || load.module && module !== load.module))
      return module;

    // already has a module value but not already in the registry (load.module)
    // means it was removed by registry.delete, so we should
    // disgard the current load record creating a new one over it
    // but keep any existing registration
    if (!load || !module && load.module)
      load = createLoadRecord(state, resolvedKey, load && load.registration);

    var link = load.linkRecord;
    if (!link)
      return load;

    return instantiate(loader, load, link, registry, state);
  });
}

function traceLoad (loader, load, link) {
  loader.loads = loader.loads || {};
  loader.loads[load.key] = {
    key: load.key,
    deps: link.dependencies,
    depMap: link.depMap || {}
  };
}

/*
 * Convert a CJS module.exports into a valid object for new Module:
 *
 *   new Module(getEsModule(module.exports))
 *
 * Sets the default value to the module, while also reading off named exports carefully.
 */
function registerDeclarative (loader, load, link, declare) {
  var moduleObj = link.moduleObj;
  var importerSetters = load.importerSetters;

  var locked = false;

  // closure especially not based on link to allow link record disposal
  var declared = declare.call(envGlobal, function (name, value) {
    // export setter propogation with locking to avoid cycles
    if (locked)
      return;

    if (typeof name === 'object') {
      for (var p in name)
        if (p !== '__useDefault')
          moduleObj[p] = name[p];
    }
    else {
      moduleObj[name] = value;
    }

    locked = true;
    for (var i = 0; i < importerSetters.length; i++)
      importerSetters[i](moduleObj);
    locked = false;

    return value;
  }, new ContextualLoader(loader, load.key));

  link.setters = declared.setters;
  link.execute = declared.execute;
  if (declared.exports)
    link.moduleObj = moduleObj = declared.exports;
}

function instantiateDeps (loader, load, link, registry, state, seen) {
  return (link.depsInstantiatePromise || (link.depsInstantiatePromise = Promise.resolve()
  .then(function () {
    var depsInstantiatePromises = Array(link.dependencies.length);

    for (var i = 0; i < link.dependencies.length; i++)
      depsInstantiatePromises[i] = resolveInstantiateDep(loader, link.dependencies[i], load.key, registry, state, loader.trace && (link.depMap = {}));

    return Promise.all(depsInstantiatePromises);
  })
  .then(function (dependencyInstantiations) {
    link.dependencyInstantiations = dependencyInstantiations;

    // run setters to set up bindings to instantiated dependencies
    if (link.setters) {
      for (var i = 0; i < dependencyInstantiations.length; i++) {
        var setter = link.setters[i];
        if (setter) {
          var instantiation = dependencyInstantiations[i];

          if (instantiation instanceof ModuleNamespace) {
            setter(instantiation);
          }
          else {
            setter(instantiation.module || instantiation.linkRecord.moduleObj);
            // this applies to both es and dynamic registrations
            if (instantiation.importerSetters)
              instantiation.importerSetters.push(setter);
          }
        }
      }
    }
  })))
  .then(function () {
    // now deeply instantiateDeps on each dependencyInstantiation that is a load record
    var deepDepsInstantiatePromises = [];

    for (var i = 0; i < link.dependencies.length; i++) {
      var depLoad = link.dependencyInstantiations[i];
      var depLink = depLoad.linkRecord;

      if (!depLink || depLink.linked)
        continue;

      if (seen.indexOf(depLoad) !== -1)
        continue;
      seen.push(depLoad);

      deepDepsInstantiatePromises.push(instantiateDeps(loader, depLoad, depLoad.linkRecord, registry, state, seen));
    }

    return Promise.all(deepDepsInstantiatePromises);
  })
  .then(function () {
    // as soon as all dependencies instantiated, we are ready for evaluation so can add to the registry
    // this can run multiple times, but so what
    link.linked = true;
    if (loader.trace)
      traceLoad(loader, load, link);

    return load;
  })
  .catch(function (err) {
    err = LoaderError__Check_error_message_for_loader_stack(err, 'Loading ' + load.key);

    // throw up the instantiateDeps stack
    // loads are then synchonously cleared at the top-level through the clearLoadErrors helper below
    // this then ensures avoiding partially unloaded tree states
    link.error = link.error || err;

    throw err;
  });
}

// clears an errored load and all its errored dependencies from the loads registry
function clearLoadErrors (loader, load) {
  var state = loader[REGISTER_INTERNAL];

  // clear from loads
  if (state.records[load.key] === load)
    delete state.records[load.key];

  var link = load.linkRecord;

  if (!link)
    return;

  if (link.dependencyInstantiations)
    link.dependencyInstantiations.forEach(function (depLoad, index) {
      if (!depLoad || depLoad instanceof ModuleNamespace)
        return;

      if (depLoad.linkRecord) {
        if (depLoad.linkRecord.error) {
          // provides a circular reference check
          if (state.records[depLoad.key] === depLoad)
            clearLoadErrors(loader, depLoad);
        }

        // unregister setters for es dependency load records that will remain
        if (link.setters && depLoad.importerSetters) {
          var setterIndex = depLoad.importerSetters.indexOf(link.setters[index]);
          depLoad.importerSetters.splice(setterIndex, 1);
        }
      }
    });
}

/*
 * System.register
 */
RegisterLoader.prototype.register = function (key, deps, declare) {
  var state = this[REGISTER_INTERNAL];

  // anonymous modules get stored as lastAnon
  if (declare === undefined) {
    state.lastRegister = [key, deps, undefined];
  }

  // everything else registers into the register cache
  else {
    var load = state.records[key] || createLoadRecord(state, key, undefined);
    load.registration = [deps, declare, undefined];
  }
};

/*
 * System.registerDyanmic
 */
RegisterLoader.prototype.registerDynamic = function (key, deps, executingRequire, execute) {
  var state = this[REGISTER_INTERNAL];

  // anonymous modules get stored as lastAnon
  if (typeof key !== 'string') {
    state.lastRegister = [key, deps, executingRequire];
  }

  // everything else registers into the register cache
  else {
    var load = state.records[key] || createLoadRecord(state, key, undefined);
    load.registration = [deps, executingRequire, execute];
  }
};

// ContextualLoader class
// backwards-compatible with previous System.register context argument by exposing .id
function ContextualLoader (loader, key) {
  this.loader = loader;
  this.key = this.id = key;
}
ContextualLoader.prototype.constructor = function () {
  throw new TypeError('Cannot subclass the contextual loader only Reflect.Loader.');
};
ContextualLoader.prototype.import = function (key) {
  return this.loader.import(key, this.key);
};
ContextualLoader.prototype.resolve = function (key) {
  return this.loader.resolve(key, this.key);
};
ContextualLoader.prototype.load = function (key) {
  return this.loader.load(key, this.key);
};

// this is the execution function bound to the Module namespace record
function ensureEvaluate (loader, load, link, registry, state, seen) {
  if (load.module)
    return load.module;

  if (link.error)
    throw link.error;

  if (seen && seen.indexOf(load) !== -1)
    return load.linkRecord.moduleObj;

  // for ES loads we always run ensureEvaluate on top-level, so empty seen is passed regardless
  // for dynamic loads, we pass seen if also dynamic
  var err = doEvaluate(loader, load, link, registry, state, link.setters ? [] : seen || []);
  if (err) {
    clearLoadErrors(loader, load);
    throw err;
  }

  return load.module;
}

function makeDynamicRequire (loader, key, dependencies, dependencyInstantiations, registry, state, seen) {
  // we can only require from already-known dependencies
  return function (name) {
    for (var i = 0; i < dependencies.length; i++) {
      if (dependencies[i] === name) {
        var depLoad = dependencyInstantiations[i];
        var module;

        if (depLoad instanceof ModuleNamespace)
          module = depLoad;
        else
          module = ensureEvaluate(loader, depLoad, depLoad.linkRecord, registry, state, seen);

        return module.__useDefault ? module.default : module;
      }
    }
    throw new Error('Module ' + name + ' not declared as a System.registerDynamic dependency of ' + key);
  };
}

// ensures the given es load is evaluated
// returns the error if any
function doEvaluate (loader, load, link, registry, state, seen) {
  seen.push(load);

  var err;

  // es modules evaluate dependencies first
  // non es modules explicitly call moduleEvaluate through require
  if (link.setters) {
    var depLoad, depLink;
    for (var i = 0; i < link.dependencies.length; i++) {
      depLoad = link.dependencyInstantiations[i];

      if (depLoad instanceof ModuleNamespace)
        continue;

      // custom Module returned from instantiate
      depLink = depLoad.linkRecord;
      if (depLink && seen.indexOf(depLoad) === -1) {
        if (depLink.error)
          err = depLink.error;
        else
          // dynamic / declarative boundaries clear the "seen" list
          // we just let cross format circular throw as would happen in real implementations
          err = doEvaluate(loader, depLoad, depLink, registry, state, depLink.setters ? seen : []);
      }

      if (err)
        return link.error = LoaderError__Check_error_message_for_loader_stack(err, 'Evaluating ' + load.key);
    }
  }

  // link.execute won't exist for Module returns from instantiate on top-level load
  if (link.execute) {
    // ES System.register execute
    // "this" is null in ES
    if (link.setters) {
      err = declarativeExecute(link.execute);
    }
    // System.registerDynamic execute
    // "this" is "exports" in CJS
    else {
      var module = { id: load.key };
      var moduleObj = link.moduleObj;
      Object.defineProperty(module, 'exports', {
        configurable: true,
        set: function (exports) {
          moduleObj.default = exports;
        },
        get: function () {
          return moduleObj.default;
        }
      });

      var require = makeDynamicRequire(loader, load.key, link.dependencies, link.dependencyInstantiations, registry, state, seen);

      // evaluate deps first
      if (!link.executingRequire)
        for (var i = 0; i < link.dependencies.length; i++)
          require(link.dependencies[i]);

      err = dynamicExecute(link.execute, require, moduleObj.default, module);

      // pick up defineProperty calls to module.exports when we can
      if (module.exports !== moduleObj.default)
        moduleObj.default = module.exports;

      // __esModule flag extension support
      if (moduleObj.default && moduleObj.default.__esModule)
        for (var p in moduleObj.default)
          if (Object.hasOwnProperty.call(moduleObj.default, p) && p !== 'default')
            moduleObj[p] = moduleObj.default[p];
    }
  }

  if (err)
    return link.error = LoaderError__Check_error_message_for_loader_stack(err, 'Evaluating ' + load.key);

  registry[load.key] = load.module = new ModuleNamespace(link.moduleObj);

  // if not an esm module, run importer setters and clear them
  // this allows dynamic modules to update themselves into es modules
  // as soon as execution has completed
  if (!link.setters) {
    if (load.importerSetters)
      for (var i = 0; i < load.importerSetters.length; i++)
        load.importerSetters[i](load.module);
    load.importerSetters = undefined;
  }

  // dispose link record
  load.linkRecord = undefined;
}

// {} is the closest we can get to call(undefined)
var nullContext = {};
if (Object.freeze)
  Object.freeze(nullContext);

function declarativeExecute (execute) {
  try {
    execute.call(nullContext);
  }
  catch (e) {
    return e;
  }
}

function dynamicExecute (execute, require, exports, module) {
  try {
    var output = execute.call(envGlobal, require, exports, module);
    if (output !== undefined)
      module.exports = output;
  }
  catch (e) {
    return e;
  }
}

if (!window.babel || !window.babelPluginTransformES2015ModulesSystemJS || !window.babelPluginSyntaxDynamicImport)
  throw new Error('babel-browser-build.js must be loaded first');

var loader;

// <script type="module"> support
var anonSources = {};
if (typeof document != 'undefined' && document.getElementsByTagName) {
  function ready() {
    document.removeEventListener('DOMContentLoaded', ready, false );

    var anonCnt = 0;

    var scripts = document.getElementsByTagName('script');
    for (var i = 0; i < scripts.length; i++) {
      var script = scripts[i];
      if (script.type == 'module' && !script.loaded) {
        script.loaded = true;
        if (script.src) {
          loader.import(script.src);
        }
        // anonymous modules supported via a custom naming scheme and registry
        else {
          var uri = './<anon' + ++anonCnt + '>';
          if (script.id !== ""){
            uri = "./" + script.id;
          }

          var anonName = resolveIfNotPlain(uri, baseURI);
          anonSources[anonName] = script.innerHTML;
          loader.import(anonName);
        }
      }
    }
  }

  // simple DOM ready
  if (document.readyState === 'complete')
    setTimeout(ready);
  else
    document.addEventListener('DOMContentLoaded', ready, false);
}

function BrowserESModuleLoader(baseKey) {
  if (baseKey)
    this.baseKey = resolveIfNotPlain(baseKey, baseURI) || resolveIfNotPlain('./' + baseKey, baseURI);

  RegisterLoader.call(this);

  var loader = this;

  // ensure System.register is available
  envGlobal.System = envGlobal.System || {};
  if (typeof envGlobal.System.register == 'function')
    var prevRegister = envGlobal.System.register;
  envGlobal.System.register = function() {
    loader.register.apply(loader, arguments);
    if (prevRegister)
      prevRegister.apply(this, arguments);
  };
}
BrowserESModuleLoader.prototype = Object.create(RegisterLoader.prototype);

// normalize is never given a relative name like "./x", that part is already handled
BrowserESModuleLoader.prototype[RegisterLoader.resolve] = function(key, parent) {
  var resolved = RegisterLoader.prototype[RegisterLoader.resolve].call(this, key, parent || this.baseKey) || key;
  if (!resolved)
    throw new RangeError('ES module loader does not resolve plain module names, resolving "' + key + '" to ' + parent);

  return resolved;
};

function xhrFetch(url, resolve, reject) {
  var xhr = new XMLHttpRequest();
  function load(source) {
    resolve(xhr.responseText);
  }
  function error() {
    reject(new Error('XHR error' + (xhr.status ? ' (' + xhr.status + (xhr.statusText ? ' ' + xhr.statusText  : '') + ')' : '') + ' loading ' + url));
  }

  xhr.onreadystatechange = function () {
    if (xhr.readyState === 4) {
      // in Chrome on file:/// URLs, status is 0
      if (xhr.status == 0) {
        if (xhr.responseText) {
          load();
        }
        else {
          // when responseText is empty, wait for load or error event
          // to inform if it is a 404 or empty file
          xhr.addEventListener('error', error);
          xhr.addEventListener('load', load);
        }
      }
      else if (xhr.status === 200) {
        load();
      }
      else {
        error();
      }
    }
  };
  xhr.open("GET", url, true);
  xhr.send(null);
}

// instantiate just needs to run System.register
// so we fetch the source, convert into the Babel System module format, then evaluate it
BrowserESModuleLoader.prototype[RegisterLoader.instantiate] = function(key, processAnonRegister) {
  var loader = this;

  // load as ES with Babel converting into System.register
  return new Promise(function(resolve, reject) {
    // anonymous module
    if (anonSources[key]) {
      resolve(anonSources[key])
      anonSources[key] = undefined;
    }
    // otherwise we fetch
    else {
      xhrFetch(key, resolve, reject);
    }
  })
  .then(function(source) {
    // transform source with Babel
    var output = babel.transform(source, {
      compact: false,
      filename: key + '!transpiled',
      sourceFileName: key,
      moduleIds: false,
      sourceMaps: 'inline',
      babelrc: false,
      plugins: [babelPluginSyntaxDynamicImport, babelPluginTransformES2015ModulesSystemJS]
    });

    // evaluate without require, exports and module variables
    // we leave module in for now to allow module.require access
    (0, eval)(output.code + '\n//# sourceURL=' + key + '!transpiled');
    processAnonRegister();
  });
};

// create a default loader instance in the browser
if (isBrowser)
  loader = new BrowserESModuleLoader();

return BrowserESModuleLoader;

})));