- 前言
- Lazy
- createWrapper
- generate
- range
- repeat
- strict
- Sequence
- define
- async
- chunk
- compact
- concat
- consecutive
- contains
- countBy
- dropWhile
- each
- equals
- every
- filter
- find
- findWhere
- first
- flatten
- get
- getIterator
- groupBy
- indexBy
- indexOf
- initial
- intersection
- invoke
- isEmpty
- join
- last
- lastIndexOf
- map
- max
- memoize
- min
- none
- ofType
- pluck
- reduce
- reduceRight
- reject
- rest
- reverse
- shuffle
- size
- some
- sort
- sortBy
- sortedIndex
- sum
- takeWhile
- tap
- toArray
- toObject
- union
- uniq
- where
- without
- zip
- ArrayLikeSequence
- define
- concat
- first
- get
- length
- map
- pop
- push
- rest
- reverse
- shift
- slice
- unshift
- ObjectLikeSequence
- define
- assign
- async
- defaults
- functions
- get
- invert
- keys
- merge
- omit
- pairs
- pick
- toArray
- toObject
- values
- watch
- StringLikeSequence
- define
- charAt
- charCodeAt
- contains
- endsWith
- first
- indexOf
- last
- lastIndexOf
- mapString
- match
- reverse
- split
- startsWith
- substring
- toLowerCase
- toUpperCase
- GeneratedSequence
- each
- length
- AsyncSequence
- contains
- each
- find
- getIterator
- indexOf
- Iterator
- current
- moveNext
- AsyncHandle
- cancel
- onComplete
- onError
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first
Creates a new sequence comprising the first N elements from this sequence, OR (if N is undefined
) simply returns the first element of this sequence.
Signature
Sequence.first = function(count) { /*...*/ }
Sequence.first = function first(count) { if (typeof count === "undefined") { return getFirst(this); } return new TakeSequence(this, count); }
Name | Type(s) | Description |
---|---|---|
count | number? | The number of elements to take from this sequence. If this value exceeds the length of the sequence, the resulting sequence will be essentially the same as this one. |
returns | * | The new sequence (or the first element from this sequence if no count was given). |
Examples
function powerOfTwo(exp) { return Math.pow(2, exp); } Lazy.generate(powerOfTwo).first() // => 1 Lazy.generate(powerOfTwo).first(5) // sequence: [1, 2, 4, 8, 16] Lazy.generate(powerOfTwo).skip(2).first() // => 4 Lazy.generate(powerOfTwo).skip(2).first(2) // sequence: [4, 8]
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