//// [for-of19.ts] for (var v of new FooIterator) { v; } class Foo { } class FooIterator { next() { return { value: new Foo, done: false }; } [Symbol.iterator]() { return this; } } //// [for-of19.js] for (var v of new FooIterator) { v; } class Foo { } class FooIterator { next() { return { value: new Foo, done: false }; } [Symbol.iterator]() { return this; } }