split-if
v1.0.4
Published
RxJS operator. Packs all the source Observable values into arrays. New array is emitted every time a predicate is fulfilled.
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split-if
RxJS operator. Packs all the source Observable values into arrays. New array is emitted every time a predicate is fulfilled.
See RxJS
Examples
Example 1 (split by value)
const {from} = require('rxjs');
const {splitIf} = require('split-if');
const src = from([4, 8, 1, 3, 5, 1, 1, 6, 8]).pipe(splitIf(x => x === 1));
const res = [];
src.subscribe(x => res.push(x));
console.log(res);
//=> [ [ 4, 8 ], [ 1, 3, 5 ], [ 1 ], [ 1, 6, 8 ] ]
Example 2 (split by index)
We can easily make a partitionN
RxJS operator using splitIf
:
import {OperatorFunction} from 'rxjs';
import {splitIf} from 'split-if';
const partitionN = <T>(n: number): OperatorFunction<T, T[]> =>
splitIf((_: T, i: number) => i % n === 0);
Let's use it:
import {from} from 'rxjs';
const src = from([4, 8, 1, 3, 5, 4, 1, 6, 8, -1, 2]).pipe(partitionN(3));
const res: number[][] = [];
src.subscribe((x: number[]) => res.push(x));
console.log(res);
//=> [ [ 4, 8, 1 ], [ 3, 5, 4 ], [ 1, 6, 8 ], [ -1, 2 ] ]
Why to use
- Typed. With
d.ts
for Javascript. - Well tested. 100% code coverage.
Installation
$ npm install split-if
Usage
Typescript / ES module:
import {splitIf} from 'split-if';
Javascript / CommonJS:
const {splitIf} = require('split-if');
API
function splitIf<T>(
predicate: (value: T, index: number) => boolean,
thisArg?: any
): OperatorFunction<T, T[]>;
Where its OperatorFunction<T, T[]>
can be substituted for:
(source: Observable<T>) => Observable<T[]>;
See: RxJS OperatorFunction
Parameters
| | | |
| --------- | -------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| T | {any} | The type of Observable's value. |
| predicate | {(value: T, index: number) => boolean} | A function that evaluates each value emitted by the source Observable
. If it returns true
, a new array of previous 'buffered' values is emitted. The index parameter is the number i for the i-th source emission that has happened since the subscription, starting from the number 0. |
| thisArg | {any} | Optional. Default is undefined. An optional argument to determine the value of this in the predicate function. |
Returns
A function that returns an Observable
that emits arrays of all items from the source Observable. These arrays are emitted every time a predicate is fulfilled.