uniIM/node_modules/systemjs/dist/system.js

/*!
 * SystemJS 6.15.1
 */
(function () {

  function errMsg(errCode, msg) {
    return (msg || "") + " (SystemJS Error#" + errCode + " " + "https://github.com/systemjs/systemjs/blob/main/docs/errors.md#" + errCode + ")";
  }

  var hasSymbol = typeof Symbol !== 'undefined';
  var hasSelf = typeof self !== 'undefined';
  var hasDocument = typeof document !== 'undefined';

  var envGlobal = hasSelf ? self : global;

  var baseUrl;

  if (hasDocument) {
    var baseEl = document.querySelector('base[href]');
    if (baseEl)
      baseUrl = baseEl.href;
  }

  if (!baseUrl && typeof location !== 'undefined') {
    baseUrl = location.href.split('#')[0].split('?')[0];
    var lastSepIndex = baseUrl.lastIndexOf('/');
    if (lastSepIndex !== -1)
      baseUrl = baseUrl.slice(0, lastSepIndex + 1);
  }

  var backslashRegEx = /\\/g;
  function resolveIfNotPlainOrUrl (relUrl, parentUrl) {
    if (relUrl.indexOf('\\') !== -1)
      relUrl = relUrl.replace(backslashRegEx, '/');
    // protocol-relative
    if (relUrl[0] === '/' && relUrl[1] === '/') {
      return parentUrl.slice(0, parentUrl.indexOf(':') + 1) + relUrl;
    }
    // relative-url
    else if (relUrl[0] === '.' && (relUrl[1] === '/' || relUrl[1] === '.' && (relUrl[2] === '/' || relUrl.length === 2 && (relUrl += '/')) ||
        relUrl.length === 1  && (relUrl += '/')) ||
        relUrl[0] === '/') {
      var parentProtocol = parentUrl.slice(0, parentUrl.indexOf(':') + 1);
      // Disabled, but these cases will give inconsistent results for deep backtracking
      //if (parentUrl[parentProtocol.length] !== '/')
      //  throw Error('Cannot resolve');
      // read pathname from parent URL
      // pathname taken to be part after leading "/"
      var pathname;
      if (parentUrl[parentProtocol.length + 1] === '/') {
        // resolving to a :// so we need to read out the auth and host
        if (parentProtocol !== 'file:') {
          pathname = parentUrl.slice(parentProtocol.length + 2);
          pathname = pathname.slice(pathname.indexOf('/') + 1);
        }
        else {
          pathname = parentUrl.slice(8);
        }
      }
      else {
        // resolving to :/ so pathname is the /... part
        pathname = parentUrl.slice(parentProtocol.length + (parentUrl[parentProtocol.length] === '/'));
      }

      if (relUrl[0] === '/')
        return parentUrl.slice(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'
      var segmented = pathname.slice(0, pathname.lastIndexOf('/') + 1) + relUrl;

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

        // new segment - check if it is relative
        else if (segmented[i] === '.') {
          // ../ segment
          if (segmented[i + 1] === '.' && (segmented[i + 2] === '/' || i + 2 === segmented.length)) {
            output.pop();
            i += 2;
          }
          // ./ segment
          else if (segmented[i + 1] === '/' || i + 1 === segmented.length) {
            i += 1;
          }
          else {
            // the start of a new segment as below
            segmentIndex = i;
          }
        }
        // it is the start of a new segment
        else {
          segmentIndex = i;
        }
      }
      // finish reading out the last segment
      if (segmentIndex !== -1)
        output.push(segmented.slice(segmentIndex));
      return parentUrl.slice(0, parentUrl.length - pathname.length) + output.join('');
    }
  }

  /*
   * Import maps implementation
   *
   * To make lookups fast we pre-resolve the entire import map
   * and then match based on backtracked hash lookups
   *
   */

  function resolveUrl (relUrl, parentUrl) {
    return resolveIfNotPlainOrUrl(relUrl, parentUrl) || (relUrl.indexOf(':') !== -1 ? relUrl : resolveIfNotPlainOrUrl('./' + relUrl, parentUrl));
  }

  function resolveAndComposePackages (packages, outPackages, baseUrl, parentMap, parentUrl) {
    for (var p in packages) {
      var resolvedLhs = resolveIfNotPlainOrUrl(p, baseUrl) || p;
      var rhs = packages[p];
      // package fallbacks not currently supported
      if (typeof rhs !== 'string')
        continue;
      var mapped = resolveImportMap(parentMap, resolveIfNotPlainOrUrl(rhs, baseUrl) || rhs, parentUrl);
      if (!mapped) {
        targetWarning('W1', p, rhs, 'bare specifier did not resolve');
      }
      else
        outPackages[resolvedLhs] = mapped;
    }
  }

  function resolveAndComposeImportMap (json, baseUrl, outMap) {
    if (json.imports)
      resolveAndComposePackages(json.imports, outMap.imports, baseUrl, outMap, null);

    var u;
    for (u in json.scopes || {}) {
      var resolvedScope = resolveUrl(u, baseUrl);
      resolveAndComposePackages(json.scopes[u], outMap.scopes[resolvedScope] || (outMap.scopes[resolvedScope] = {}), baseUrl, outMap, resolvedScope);
    }

    for (u in json.depcache || {})
      outMap.depcache[resolveUrl(u, baseUrl)] = json.depcache[u];
    
    for (u in json.integrity || {})
      outMap.integrity[resolveUrl(u, baseUrl)] = json.integrity[u];
  }

  function getMatch (path, matchObj) {
    if (matchObj[path])
      return path;
    var sepIndex = path.length;
    do {
      var segment = path.slice(0, sepIndex + 1);
      if (segment in matchObj)
        return segment;
    } while ((sepIndex = path.lastIndexOf('/', sepIndex - 1)) !== -1)
  }

  function applyPackages (id, packages) {
    var pkgName = getMatch(id, packages);
    if (pkgName) {
      var pkg = packages[pkgName];
      if (pkg === null) return;
      if (id.length > pkgName.length && pkg[pkg.length - 1] !== '/') {
        targetWarning('W2', pkgName, pkg, "should have a trailing '/'");
      }
      else
        return pkg + id.slice(pkgName.length);
    }
  }

  function targetWarning (code, match, target, msg) {
    console.warn(errMsg(code, "Package target " + msg + ", resolving target '" + target + "' for " + match));
  }

  function resolveImportMap (importMap, resolvedOrPlain, parentUrl) {
    var scopes = importMap.scopes;
    var scopeUrl = parentUrl && getMatch(parentUrl, scopes);
    while (scopeUrl) {
      var packageResolution = applyPackages(resolvedOrPlain, scopes[scopeUrl]);
      if (packageResolution)
        return packageResolution;
      scopeUrl = getMatch(scopeUrl.slice(0, scopeUrl.lastIndexOf('/')), scopes);
    }
    return applyPackages(resolvedOrPlain, importMap.imports) || resolvedOrPlain.indexOf(':') !== -1 && resolvedOrPlain;
  }

  /*
   * SystemJS Core
   *
   * Provides
   * - System.import
   * - System.register support for
   *     live bindings, function hoisting through circular references,
   *     reexports, dynamic import, import.meta.url, top-level await
   * - System.getRegister to get the registration
   * - Symbol.toStringTag support in Module objects
   * - Hookable System.createContext to customize import.meta
   * - System.onload(err, id, deps) handler for tracing / hot-reloading
   *
   * Core comes with no System.prototype.resolve or
   * System.prototype.instantiate implementations
   */

  var toStringTag$1 = hasSymbol && Symbol.toStringTag;
  var REGISTRY = hasSymbol ? Symbol() : '@';

  function SystemJS () {
    this[REGISTRY] = {};
  }

  var systemJSPrototype = SystemJS.prototype;

  systemJSPrototype.import = function (id, parentUrl, meta) {
    var loader = this;
    (parentUrl && typeof parentUrl === 'object') && (meta = parentUrl, parentUrl = undefined);
    return Promise.resolve(loader.prepareImport())
    .then(function() {
      return loader.resolve(id, parentUrl, meta);
    })
    .then(function (id) {
      var load = getOrCreateLoad(loader, id, undefined, meta);
      return load.C || topLevelLoad(loader, load);
    });
  };

  // Hookable createContext function -> allowing eg custom import meta
  systemJSPrototype.createContext = function (parentId) {
    var loader = this;
    return {
      url: parentId,
      resolve: function (id, parentUrl) {
        return Promise.resolve(loader.resolve(id, parentUrl || parentId));
      }
    };
  };

  // onLoad(err, id, deps) provided for tracing / hot-reloading
  systemJSPrototype.onload = function () {};
  function loadToId (load) {
    return load.id;
  }
  function triggerOnload (loader, load, err, isErrSource) {
    loader.onload(err, load.id, load.d && load.d.map(loadToId), !!isErrSource);
    if (err)
      throw err;
  }

  var lastRegister;
  systemJSPrototype.register = function (deps, declare, metas) {
    lastRegister = [deps, declare, metas];
  };

  /*
   * getRegister provides the last anonymous System.register call
   */
  systemJSPrototype.getRegister = function () {
    var _lastRegister = lastRegister;
    lastRegister = undefined;
    return _lastRegister;
  };

  function getOrCreateLoad (loader, id, firstParentUrl, meta) {
    var load = loader[REGISTRY][id];
    if (load)
      return load;

    var importerSetters = [];
    var ns = Object.create(null);
    if (toStringTag$1)
      Object.defineProperty(ns, toStringTag$1, { value: 'Module' });

    var instantiatePromise = Promise.resolve()
    .then(function () {
      return loader.instantiate(id, firstParentUrl, meta);
    })
    .then(function (registration) {
      if (!registration)
        throw Error(errMsg(2, 'Module ' + id + ' did not instantiate'));
      function _export (name, value) {
        // note if we have hoisted exports (including reexports)
        load.h = true;
        var changed = false;
        if (typeof name === 'string') {
          if (!(name in ns) || ns[name] !== value) {
            ns[name] = value;
            changed = true;
          }
        }
        else {
          for (var p in name) {
            var value = name[p];
            if (!(p in ns) || ns[p] !== value) {
              ns[p] = value;
              changed = true;
            }
          }

          if (name && name.__esModule) {
            ns.__esModule = name.__esModule;
          }
        }
        if (changed)
          for (var i = 0; i < importerSetters.length; i++) {
            var setter = importerSetters[i];
            if (setter) setter(ns);
          }
        return value;
      }
      var declared = registration[1](_export, registration[1].length === 2 ? {
        import: function (importId, meta) {
          return loader.import(importId, id, meta);
        },
        meta: loader.createContext(id)
      } : undefined);
      load.e = declared.execute || function () {};
      return [registration[0], declared.setters || [], registration[2] || []];
    }, function (err) {
      load.e = null;
      load.er = err;
      triggerOnload(loader, load, err, true);
      throw err;
    });

    var linkPromise = instantiatePromise
    .then(function (instantiation) {
      return Promise.all(instantiation[0].map(function (dep, i) {
        var setter = instantiation[1][i];
        var meta = instantiation[2][i];
        return Promise.resolve(loader.resolve(dep, id))
        .then(function (depId) {
          var depLoad = getOrCreateLoad(loader, depId, id, meta);
          // depLoad.I may be undefined for already-evaluated
          return Promise.resolve(depLoad.I)
          .then(function () {
            if (setter) {
              depLoad.i.push(setter);
              // only run early setters when there are hoisted exports of that module
              // the timing works here as pending hoisted export calls will trigger through importerSetters
              if (depLoad.h || !depLoad.I)
                setter(depLoad.n);
            }
            return depLoad;
          });
        });
      }))
      .then(function (depLoads) {
        load.d = depLoads;
      });
    });

    // Capital letter = a promise function
    return load = loader[REGISTRY][id] = {
      id: id,
      // importerSetters, the setters functions registered to this dependency
      // we retain this to add more later
      i: importerSetters,
      // module namespace object
      n: ns,
      // extra module information for import assertion
      // shape like: { assert: { type: 'xyz' } }
      m: meta,

      // instantiate
      I: instantiatePromise,
      // link
      L: linkPromise,
      // whether it has hoisted exports
      h: false,

      // On instantiate completion we have populated:
      // dependency load records
      d: undefined,
      // execution function
      e: undefined,

      // On execution we have populated:
      // the execution error if any
      er: undefined,
      // in the case of TLA, the execution promise
      E: undefined,

      // On execution, L, I, E cleared

      // Promise for top-level completion
      C: undefined,

      // parent instantiator / executor
      p: undefined
    };
  }

  function instantiateAll (loader, load, parent, loaded) {
    if (!loaded[load.id]) {
      loaded[load.id] = true;
      // load.L may be undefined for already-instantiated
      return Promise.resolve(load.L)
      .then(function () {
        if (!load.p || load.p.e === null)
          load.p = parent;
        return Promise.all(load.d.map(function (dep) {
          return instantiateAll(loader, dep, parent, loaded);
        }));
      })
      .catch(function (err) {
        if (load.er)
          throw err;
        load.e = null;
        triggerOnload(loader, load, err, false);
        throw err;
      });
    }
  }

  function topLevelLoad (loader, load) {
    return load.C = instantiateAll(loader, load, load, {})
    .then(function () {
      return postOrderExec(loader, load, {});
    })
    .then(function () {
      return load.n;
    });
  }

  // the closest we can get to call(undefined)
  var nullContext = Object.freeze(Object.create(null));

  // returns a promise if and only if a top-level await subgraph
  // throws on sync errors
  function postOrderExec (loader, load, seen) {
    if (seen[load.id])
      return;
    seen[load.id] = true;

    if (!load.e) {
      if (load.er)
        throw load.er;
      if (load.E)
        return load.E;
      return;
    }

    // From here we're about to execute the load.
    // Because the execution may be async, we pop the `load.e` first.
    // So `load.e === null` always means the load has been executed or is executing.
    // To inspect the state:
    // - If `load.er` is truthy, the execution has threw or has been rejected;
    // - otherwise, either the `load.E` is a promise, means it's under async execution, or
    // - the `load.E` is null, means the load has completed the execution or has been async resolved.
    var exec = load.e;
    load.e = null;

    // deps execute first, unless circular
    var depLoadPromises;
    load.d.forEach(function (depLoad) {
      try {
        var depLoadPromise = postOrderExec(loader, depLoad, seen);
        if (depLoadPromise)
          (depLoadPromises = depLoadPromises || []).push(depLoadPromise);
      }
      catch (err) {
        load.er = err;
        triggerOnload(loader, load, err, false);
        throw err;
      }
    });
    if (depLoadPromises)
      return Promise.all(depLoadPromises).then(doExec);

    return doExec();

    function doExec () {
      try {
        var execPromise = exec.call(nullContext);
        if (execPromise) {
          execPromise = execPromise.then(function () {
            load.C = load.n;
            load.E = null; // indicates completion
            if (!false) triggerOnload(loader, load, null, true);
          }, function (err) {
            load.er = err;
            load.E = null;
            if (!false) triggerOnload(loader, load, err, true);
            throw err;
          });
          return load.E = execPromise;
        }
        // (should be a promise, but a minify optimization to leave out Promise.resolve)
        load.C = load.n;
        load.L = load.I = undefined;
      }
      catch (err) {
        load.er = err;
        throw err;
      }
      finally {
        triggerOnload(loader, load, load.er, true);
      }
    }
  }

  envGlobal.System = new SystemJS();

  /*
   * SystemJS browser attachments for script and import map processing
   */

  var importMapPromise = Promise.resolve();
  var importMap = { imports: {}, scopes: {}, depcache: {}, integrity: {} };

  // Scripts are processed immediately, on the first System.import, and on DOMReady.
  // Import map scripts are processed only once (by being marked) and in order for each phase.
  // This is to avoid using DOM mutation observers in core, although that would be an alternative.
  var processFirst = hasDocument;
  systemJSPrototype.prepareImport = function (doProcessScripts) {
    if (processFirst || doProcessScripts) {
      processScripts();
      processFirst = false;
    }
    return importMapPromise;
  };

  systemJSPrototype.getImportMap = function () {
    return JSON.parse(JSON.stringify(importMap));
  };

  if (hasDocument) {
    processScripts();
    window.addEventListener('DOMContentLoaded', processScripts);
  }
  systemJSPrototype.addImportMap = function (newMap, mapBase) {
    resolveAndComposeImportMap(newMap, mapBase || baseUrl, importMap);
  };

  function processScripts () {
    [].forEach.call(document.querySelectorAll('script'), function (script) {
      if (script.sp) // sp marker = systemjs processed
        return;
      // TODO: deprecate systemjs-module in next major now that we have auto import
      if (script.type === 'systemjs-module') {
        script.sp = true;
        if (!script.src)
          return;
        System.import(script.src.slice(0, 7) === 'import:' ? script.src.slice(7) : resolveUrl(script.src, baseUrl)).catch(function (e) {
          // if there is a script load error, dispatch an "error" event
          // on the script tag.
          if (e.message.indexOf('https://github.com/systemjs/systemjs/blob/main/docs/errors.md#3') > -1) {
            var event = document.createEvent('Event');
            event.initEvent('error', false, false);
            script.dispatchEvent(event);
          }
          return Promise.reject(e);
        });
      }
      else if (script.type === 'systemjs-importmap') {
        script.sp = true;
        // The passThrough property is for letting the module types fetch implementation know that this is not a SystemJS module.
        var fetchPromise = script.src ? (System.fetch || fetch)(script.src, { integrity: script.integrity, priority: script.fetchPriority, passThrough: true }).then(function (res) {
          if (!res.ok)
            throw Error('Invalid status code: ' + res.status);
          return res.text();
        }).catch(function (err) {
          err.message = errMsg('W4', 'Error fetching systemjs-import map ' + script.src) + '\n' + err.message;
          console.warn(err);
          if (typeof script.onerror === 'function') {
              script.onerror();
          }
          return '{}';
        }) : script.innerHTML;
        importMapPromise = importMapPromise.then(function () {
          return fetchPromise;
        }).then(function (text) {
          extendImportMap(importMap, text, script.src || baseUrl);
        });
      }
    });
  }

  function extendImportMap (importMap, newMapText, newMapUrl) {
    var newMap = {};
    try {
      newMap = JSON.parse(newMapText);
    } catch (err) {
      console.warn(Error((errMsg('W5', "systemjs-importmap contains invalid JSON") + '\n\n' + newMapText + '\n' )));
    }
    resolveAndComposeImportMap(newMap, newMapUrl, importMap);
  }

  /*
   * Script instantiation loading
   */

  if (hasDocument) {
    window.addEventListener('error', function (evt) {
      lastWindowErrorUrl = evt.filename;
      lastWindowError = evt.error;
    });
    var baseOrigin = location.origin;
  }

  systemJSPrototype.createScript = function (url) {
    var script = document.createElement('script');
    script.async = true;
    // Only add cross origin for actual cross origin
    // this is because Safari triggers for all
    // - https://bugs.webkit.org/show_bug.cgi?id=171566
    if (url.indexOf(baseOrigin + '/'))
      script.crossOrigin = 'anonymous';
    var integrity = importMap.integrity[url];
    if (integrity)
      script.integrity = integrity;
    script.src = url;
    return script;
  };

  // Auto imports -> script tags can be inlined directly for load phase
  var lastAutoImportDeps, lastAutoImportTimeout;
  var autoImportCandidates = {};
  var systemRegister = systemJSPrototype.register;
  systemJSPrototype.register = function (deps, declare) {
    if (hasDocument && document.readyState === 'loading' && typeof deps !== 'string') {
      var scripts = document.querySelectorAll('script[src]');
      var lastScript = scripts[scripts.length - 1];
      if (lastScript) {
        lastScript.src;
        lastAutoImportDeps = deps;
        // if this is already a System load, then the instantiate has already begun
        // so this re-import has no consequence
        var loader = this;
        lastAutoImportTimeout = setTimeout(function () {
          autoImportCandidates[lastScript.src] = [deps, declare];
          loader.import(lastScript.src);
        });
      }
    }
    else {
      lastAutoImportDeps = undefined;
    }
    return systemRegister.call(this, deps, declare);
  };

  var lastWindowErrorUrl, lastWindowError;
  systemJSPrototype.instantiate = function (url, firstParentUrl) {
    var autoImportRegistration = autoImportCandidates[url];
    if (autoImportRegistration) {
      delete autoImportCandidates[url];
      return autoImportRegistration;
    }
    var loader = this;
    return Promise.resolve(systemJSPrototype.createScript(url)).then(function (script) {
      return new Promise(function (resolve, reject) {
        script.addEventListener('error', function () {
          reject(Error(errMsg(3, 'Error loading ' + url + (firstParentUrl ? ' from ' + firstParentUrl : ''))));
        });
        script.addEventListener('load', function () {
          document.head.removeChild(script);
          // Note that if an error occurs that isn't caught by this if statement,
          // that getRegister will return null and a "did not instantiate" error will be thrown.
          if (lastWindowErrorUrl === url) {
            reject(lastWindowError);
          }
          else {
            var register = loader.getRegister(url);
            // Clear any auto import registration for dynamic import scripts during load
            if (register && register[0] === lastAutoImportDeps)
              clearTimeout(lastAutoImportTimeout);
            resolve(register);
          }
        });
        document.head.appendChild(script);
      });
    });
  };

  /*
   * Fetch loader, sets up shouldFetch and fetch hooks
   */
  systemJSPrototype.shouldFetch = function () {
    return false;
  };
  if (typeof fetch !== 'undefined')
    systemJSPrototype.fetch = fetch;

  var instantiate = systemJSPrototype.instantiate;
  var jsContentTypeRegEx = /^(text|application)\/(x-)?javascript(;|$)/;
  systemJSPrototype.instantiate = function (url, parent, meta) {
    var loader = this;
    if (!this.shouldFetch(url, parent, meta))
      return instantiate.apply(this, arguments);
    return this.fetch(url, {
      credentials: 'same-origin',
      integrity: importMap.integrity[url],
      meta: meta,
    })
    .then(function (res) {
      if (!res.ok)
        throw Error(errMsg(7, res.status + ' ' + res.statusText + ', loading ' + url + (parent ? ' from ' + parent : '')));
      var contentType = res.headers.get('content-type');
      if (!contentType || !jsContentTypeRegEx.test(contentType))
        throw Error(errMsg(4, 'Unknown Content-Type "' + contentType + '", loading ' + url + (parent ? ' from ' + parent : '')));
      return res.text().then(function (source) {
        if (source.indexOf('//# sourceURL=') < 0)
          source += '\n//# sourceURL=' + url;
        (0, eval)(source);
        return loader.getRegister(url);
      });
    });
  };

  systemJSPrototype.resolve = function (id, parentUrl) {
    parentUrl = parentUrl || !true  || baseUrl;
    return resolveImportMap((importMap), resolveIfNotPlainOrUrl(id, parentUrl) || id, parentUrl) || throwUnresolved(id, parentUrl);
  };

  function throwUnresolved (id, parentUrl) {
    throw Error(errMsg(8, "Unable to resolve bare specifier '" + id + (parentUrl ? "' from " + parentUrl : "'")));
  }

  var systemInstantiate = systemJSPrototype.instantiate;
  systemJSPrototype.instantiate = function (url, firstParentUrl, meta) {
    var preloads = (importMap).depcache[url];
    if (preloads) {
      for (var i = 0; i < preloads.length; i++)
        getOrCreateLoad(this, this.resolve(preloads[i], url), url);
    }
    return systemInstantiate.call(this, url, firstParentUrl, meta);
  };

  /*
   * Supports loading System.register in workers
   */

  if (hasSelf && typeof importScripts === 'function')
    systemJSPrototype.instantiate = function (url) {
      var loader = this;
      return Promise.resolve().then(function () {
        importScripts(url);
        return loader.getRegister(url);
      });
    };

  /*
   * SystemJS global script loading support
   * Extra for the s.js build only
   * (Included by default in system.js build)
   */
  (function (global) {
    var systemJSPrototype = global.System.constructor.prototype;

    // safari unpredictably lists some new globals first or second in object order
    var firstGlobalProp, secondGlobalProp, lastGlobalProp;
    function getGlobalProp (useFirstGlobalProp) {
      var cnt = 0;
      var foundLastProp, result;
      for (var p in global) {
        // do not check frames cause it could be removed during import
        if (shouldSkipProperty(p))
          continue;
        if (cnt === 0 && p !== firstGlobalProp || cnt === 1 && p !== secondGlobalProp)
          return p;
        if (foundLastProp) {
          lastGlobalProp = p;
          result = useFirstGlobalProp && result || p;
        }
        else {
          foundLastProp = p === lastGlobalProp;
        }
        cnt++;
      }
      return result;
    }

    function noteGlobalProps () {
      // alternatively Object.keys(global).pop()
      // but this may be faster (pending benchmarks)
      firstGlobalProp = secondGlobalProp = undefined;
      for (var p in global) {
        // do not check frames cause it could be removed during import
        if (shouldSkipProperty(p))
          continue;
        if (!firstGlobalProp)
          firstGlobalProp = p;
        else if (!secondGlobalProp)
          secondGlobalProp = p;
        lastGlobalProp = p;
      }
      return lastGlobalProp;
    }

    var impt = systemJSPrototype.import;
    systemJSPrototype.import = function (id, parentUrl, meta) {
      noteGlobalProps();
      return impt.call(this, id, parentUrl, meta);
    };

    var emptyInstantiation = [[], function () { return {} }];

    var getRegister = systemJSPrototype.getRegister;
    systemJSPrototype.getRegister = function () {
      var lastRegister = getRegister.call(this);
      if (lastRegister)
        return lastRegister;

      // no registration -> attempt a global detection as difference from snapshot
      // when multiple globals, we take the global value to be the last defined new global object property
      // for performance, this will not support multi-version / global collisions as previous SystemJS versions did
      // note in Edge, deleting and re-adding a global does not change its ordering
      var globalProp = getGlobalProp(this.firstGlobalProp);
      if (!globalProp)
        return emptyInstantiation;

      var globalExport;
      try {
        globalExport = global[globalProp];
      }
      catch (e) {
        return emptyInstantiation;
      }

      return [[], function (_export) {
        return {
          execute: function () {
            _export(globalExport);
            _export({ default: globalExport, __useDefault: true });
          }
        };
      }];
    };

    var isIE11 = typeof navigator !== 'undefined' && navigator.userAgent.indexOf('Trident') !== -1;

    function shouldSkipProperty(p) {
      return !global.hasOwnProperty(p)
        || !isNaN(p) && p < global.length
        || isIE11 && global[p] && typeof window !== 'undefined' && global[p].parent === window;
    }
  })(typeof self !== 'undefined' ? self : global);

  /*
   * Loads JSON, CSS, Wasm module types based on file extension
   * filters and content type verifications
   */
  (function(global) {
    var systemJSPrototype = global.System.constructor.prototype;

    var moduleTypesRegEx = /^[^#?]+\.(css|html|json|wasm)([?#].*)?$/;
    var _shouldFetch = systemJSPrototype.shouldFetch.bind(systemJSPrototype);
    systemJSPrototype.shouldFetch = function (url) {
      return _shouldFetch(url) || moduleTypesRegEx.test(url);
    };

    var jsonContentType = /^application\/json(;|$)/;
    var cssContentType = /^text\/css(;|$)/;
    var wasmContentType = /^application\/wasm(;|$)/;

    var fetch = systemJSPrototype.fetch;
    systemJSPrototype.fetch = function (url, options) {
      return fetch(url, options)
      .then(function (res) {
        if (options.passThrough)
          return res;

        if (!res.ok)
          return res;
        var contentType = res.headers.get('content-type');
        if (jsonContentType.test(contentType))
          return res.json()
          .then(function (json) {
            return new Response(new Blob([
              'System.register([],function(e){return{execute:function(){e("default",' + JSON.stringify(json) + ')}}})'
            ], {
              type: 'application/javascript'
            }));
          });
        if (cssContentType.test(contentType))
          return res.text()
          .then(function (source) {
            source = source.replace(/url\(\s*(?:(["'])((?:\\.|[^\n\\"'])+)\1|((?:\\.|[^\s,"'()\\])+))\s*\)/g, function (match, quotes, relUrl1, relUrl2) {
              return ['url(', quotes, resolveUrl(relUrl1 || relUrl2, url), quotes, ')'].join('');
            });
            return new Response(new Blob([
              'System.register([],function(e){return{execute:function(){var s=new CSSStyleSheet();s.replaceSync(' + JSON.stringify(source) + ');e("default",s)}}})'
            ], {
              type: 'application/javascript'
            }));
          });
        if (wasmContentType.test(contentType))
          return (WebAssembly.compileStreaming ? WebAssembly.compileStreaming(res) : res.arrayBuffer().then(WebAssembly.compile))
          .then(function (module) {
            if (!global.System.wasmModules)
              global.System.wasmModules = Object.create(null);
            global.System.wasmModules[url] = module;
            // we can only set imports if supported (eg early Safari doesnt support)
            var deps = [];
            var setterSources = [];
            if (WebAssembly.Module.imports)
              WebAssembly.Module.imports(module).forEach(function (impt) {
                var key = JSON.stringify(impt.module);
                if (deps.indexOf(key) === -1) {
                  deps.push(key);
                  setterSources.push('function(m){i[' + key + ']=m}');
                }
              });
            return new Response(new Blob([
              'System.register([' + deps.join(',') + '],function(e){var i={};return{setters:[' + setterSources.join(',') +
              '],execute:function(){return WebAssembly.instantiate(System.wasmModules[' + JSON.stringify(url) +
              '],i).then(function(m){e(m.exports)})}}})'
            ], {
              type: 'application/javascript'
            }));
          });
        return res;
      });
    };
  })(typeof self !== 'undefined' ? self : global);

  var toStringTag = typeof Symbol !== 'undefined' && Symbol.toStringTag;

  systemJSPrototype.get = function (id) {
    var load = this[REGISTRY][id];
    if (load && load.e === null && !load.E) {
      if (load.er)
        return null;
      return load.n;
    }
  };

  systemJSPrototype.set = function (id, module) {
    {
      try {
        // No page-relative URLs allowed
        new URL(id);
      } catch (err) {
        console.warn(Error(errMsg('W3', '"' + id + '" is not a valid URL to set in the module registry')));
      }
    }
    var ns;
    if (toStringTag && module[toStringTag] === 'Module') {
      ns = module;
    }
    else {
      ns = Object.assign(Object.create(null), module);
      if (toStringTag)
        Object.defineProperty(ns, toStringTag, { value: 'Module' });
    }

    var done = Promise.resolve(ns);

    var load = this[REGISTRY][id] || (this[REGISTRY][id] = {
      id: id,
      i: [],
      h: false,
      d: [],
      e: null,
      er: undefined,
      E: undefined
    });

    if (load.e || load.E)
      return false;
    
    Object.assign(load, {
      n: ns,
      I: undefined,
      L: undefined,
      C: done
    });
    return ns;
  };

  systemJSPrototype.has = function (id) {
    var load = this[REGISTRY][id];
    return !!load;
  };

  // Delete function provided for hot-reloading use cases
  systemJSPrototype.delete = function (id) {
    var registry = this[REGISTRY];
    var load = registry[id];
    // in future we can support load.E case by failing load first
    // but that will require TLA callbacks to be implemented
    if (!load || (load.p && load.p.e !== null) || load.E)
      return false;

    var importerSetters = load.i;
    // remove from importerSetters
    // (release for gc)
    if (load.d)
      load.d.forEach(function (depLoad) {
        var importerIndex = depLoad.i.indexOf(load);
        if (importerIndex !== -1)
          depLoad.i.splice(importerIndex, 1);
      });
    delete registry[id];
    return function () {
      var load = registry[id];
      if (!load || !importerSetters || load.e !== null || load.E)
        return false;
      // add back the old setters
      importerSetters.forEach(function (setter) {
        load.i.push(setter);
        setter(load.n);
      });
      importerSetters = null;
    };
  };

  var iterator = typeof Symbol !== 'undefined' && Symbol.iterator;

  systemJSPrototype.entries = function () {
    var loader = this, keys = Object.keys(loader[REGISTRY]);
    var index = 0, ns, key;
    var result = {
      next: function () {
        while (
          (key = keys[index++]) !== undefined && 
          (ns = loader.get(key)) === undefined
        );
        return {
          done: key === undefined,
          value: key !== undefined && [key, ns]
        };
      }
    };

    result[iterator] = function() { return this };

    return result;
  };

})();