Creation Operators

Use this page to find the creation operator implemented by the Observable type that fits your needs:

Static methods
I want to create a new sequence	using custom logic		Observable.create
that works like a for-loop		Observable.generate
and emits the values over time	Observable.generateWithRelativeTime
Observable.generateWithAbsoluteTime
that returns a value		Observable.return/just
multiple times	Observable.repeat
that throws an error	Observable.throw
that completes	Observable.empty
that never does anything	Observable.never
from an event		Observable.fromEvent
that uses custom functions to add and remove event handlers	Observable.fromEventPattern
from an ES6 Promise	Observable.fromPromise
that iterates	over the values in an array		Observable.fromArray
of object key/values	Observable.pairs
of asynchronous elements	Observable.for
over values in a numeric range	Observable.range
over the values in an iterable, array or array-like object	Observable.from
over arguments	Observable.of
that emits values on a timer		Observable.interval
with an optional initial delay	Observable.timer
that calls a function with no arguments	on a specific scheduler	Observable.start
asynchronously	Observable.startAsync
decided at subscribe-time	based on a boolean condition	Observable.if
from a pre-set set of sequences	Observable.case
using custom logic		Observable.defer
that depends on a resource	Observable.using
I want to wrap a function		and yield the result in a sequence	Observable.toAsync	which accepts a callback	Observable.fromCallback
which accepts a Node.js callback	Observable.fromNodeCallback
I want to combine multiple sequences	and only receive values from the sequence that yields a value first	Observable.amb
and be notified when all of them have finished	Observable.forkJoin
and output the values from all of them	Observable.merge
in order	reusing the latest value when unchanged	Observable.combineLatest
using each value only once	Observable.zip
by subscribing to each in order	when the previous sequence completes	Observable.concat
when the previous sequence errors	Observable.catch
regardless of whether the previous sequence completes or errors	Observable.onErrorResumeNext
by responding to different combinations of values (join calculus)	Observable.when

See Also ##

Reference

• Observable

Concepts

• Querying Observable Sequences
• Operators By Category