ReactiveX / rxjs / 4365

97%

Pull #2474

travis-ci

fix(forEach): fix a temporal dead zone issue in forEach.

According to the ES6 spec and the implementation in V8, accessing a lexically scoped construct like const or let before it is assigned is a ReferenceError. Unlike var, it is not implicitly undefined. Because the closure handed to subscribe is immediately invoked and accesses `subscription` before it is assigned, this causes a ReferenceError in compliant engines.

The error is only triggered when running in plain ES6, i.e. without transpilation.

2 of 2 new or added lines in 1 file covered. (100.0%)

6553 of 6708 relevant lines covered (97.69%)

670.6 hits per line