API · Select

slice()

Emit values from a zero-based start index up to, but not including, an end index.

Signature

slice(start: number, end?: number): Exstream<T, C>

Example

exstream(['a', 'b', 'c', 'd']).slice(1, 3).valuesSync()
// ['b', 'c']

Parameters

start

Type numberRequired

Inclusive zero-based lower bound. Values below zero effectively start at the first input.

end

Type numberDefault Infinity

Exclusive upper bound. Fractions are accepted and compared directly against integer input indexes.

Behavior

Both bounds are parsed with parseFloat; the TypeScript API intentionally accepts numbers. start must be lower than end, and neither may parse to NaN. slice(0, Infinity) returns the same stream instance without adding an operator.

The operator preserves order and context and adds no queue. Reaching a finite end destroys this branch and releases upstream demand. It may read the value at index end to discover that the range has finished, but that value is not emitted. Existing record errors pass through and do not advance the successful-value index.

Forms

stream.slice(10, 20)
exstream.pipeline().slice(10, 20)
exstream.slice(10, 20, stream)
stream.through(exstream.slice(10, 20))

Related

take(), drop(), head()