take
accepts
1 input stream,
an amount
-
❯When the input stream emits its n-th value:
- if n <
amount, the value is emitted - if n ==
amount, the value is emitted and the stream immediately completes
- if n <
returns
a new stream of at most amount values
takeWhile
accepts
1 input stream,
a predicate function
-
❯When the input stream emits a value, it is given to the
predicate:- If the
predicatereturns✔ true, the value is emitted - otherwise, the value is ignored and the stream immediately completes
- If the
returns a new stream of filtered values
Revised on Monday, 8 Oct. 2018
Exercise
In the animation above, can you spot the difference between the outputs? Can you explain why?
Answer: the ◉ complete notification happens at a different moment:
- On the one hand,
❚ takereturns a stream that emits at most amount values and can complete as soon as this amount is reached. - On the other hand,
❚ takeWhilehas to wait for the predicate to return✘ falsein order to complete.
See also
Freelance Developer Advocate. Motion graphics with code. JavaScript and Elm. cedricsoulas.com
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