feat(throwIfEmpty): adds throwIfEmpty operator

[benlesh]

This is a new, simple, operator that will emit an error if the source observable completes without emitting a value. This primitive operator can be used to compose other operators such as first and last, and is a good compliment for defaultIfEmpty.

This is a step toward refactoring a few other operators to be smaller.

[benlesh]

Having this operator basically means that first would become:

first() => pipe(take(1), throwIfEmpty())
first(predicate) => pipe(filter(predicate), take(1), throwIfEmpty())
first(undefined, defaultValue) => pipe(take(1), defaultIfEmpty(defaultValue))
first(predicate, defaultValue) => pipe(filter(predicate), take(1), defaultIfEmpty(defaultValue))

last would be similar, only with takeLast

[rxjs-bot]

	Messages
📖

CJS: 1314.7KB, global: 698.0KB (gzipped: 114.3KB), min: 134.7KB (gzipped: 29.7KB)

Generated by 🚫 dangerJS

[coveralls]

Coverage decreased (-0.04%) to 97.501% when pulling 5749019 on benlesh:add-throwIfEmpty into 72d9745 on ReactiveX:master.

[jasonaden]

Minor change.

[jasonaden]

click

[jayphelps]

TIL this works

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.