esnext.observable.from.js 1.5 KB

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  1. 'use strict';
  2. var $ = require('../internals/export');
  3. var getBuiltIn = require('../internals/get-built-in');
  4. var call = require('../internals/function-call');
  5. var anObject = require('../internals/an-object');
  6. var isConstructor = require('../internals/is-constructor');
  7. var getIterator = require('../internals/get-iterator');
  8. var getIteratorMethod = require('../internals/get-iterator-method');
  9. var getMethod = require('../internals/get-method');
  10. var iterate = require('../internals/iterate');
  11. var wellKnownSymbol = require('../internals/well-known-symbol');
  12. var $$OBSERVABLE = wellKnownSymbol('observable');
  13. // `Observable.from` method
  14. // https://github.com/tc39/proposal-observable
  15. $({ target: 'Observable', stat: true, forced: true }, {
  16. from: function from(x) {
  17. var C = isConstructor(this) ? this : getBuiltIn('Observable');
  18. var observableMethod = getMethod(anObject(x), $$OBSERVABLE);
  19. if (observableMethod) {
  20. var observable = anObject(call(observableMethod, x));
  21. return observable.constructor === C ? observable : new C(function (observer) {
  22. return observable.subscribe(observer);
  23. });
  24. }
  25. var iteratorMethod = getIteratorMethod(x);
  26. // validate that x is iterable synchronously during `from()` call
  27. if (!iteratorMethod) getIterator(x);
  28. return new C(function (observer) {
  29. iterate(getIterator(x, iteratorMethod), function (it, stop) {
  30. observer.next(it);
  31. if (observer.closed) return stop();
  32. }, { IS_ITERATOR: true, INTERRUPTED: true });
  33. observer.complete();
  34. });
  35. }
  36. });