skipWhile

Returns an Observable that skips all items emitted by the source Observable as long as a specified condition holds true, but emits all further source items as soon as the condition becomes false.

skipWhile<T>(predicate: (value: T, index: number) => boolean): MonoTypeOperatorFunction<T>

Parameters

predicate

A function to test each item emitted from the source Observable.

Returns

MonoTypeOperatorFunction<T>: A function that returns an Observable that begins emitting items emitted by the source Observable when the specified predicate becomes false.

Description

Skips all the notifications with a truthy predicate. It will not skip the notifications when the predicate is falsy. It can also be skipped using index. Once the predicate is true, it will not be called again.

Example

Using Value: Skip some super heroes

import { from } from 'rxjs';
import { skipWhile } from 'rxjs/operators';

const source = from(['Green Arrow', 'SuperMan', 'Flash', 'SuperGirl', 'Black Canary'])
// Skip the heroes until SuperGirl
const example = source.pipe(skipWhile((hero) => hero !== 'SuperGirl'));
// output: SuperGirl, Black Canary
example.subscribe((femaleHero) => console.log(femaleHero));

Using Index: Skip value from the array until index 5

import { from } from 'rxjs';
import { skipWhile } from 'rxjs/operators';

const source = from([1, 2, 3, 4, 5, 6, 7, 9, 10]);
const example = source.pipe(skipWhile((_, i) => i !== 5));
// output: 6, 7, 9, 10
example.subscribe((val) => console.log(val));

Overloads

skipWhile(predicate: BooleanConstructor): OperatorFunction<T, Extract<T, Falsy> extends never ? never : T>

Parameters

predicate

Type: BooleanConstructor.

Returns

OperatorFunction<T, Extract<T, Falsy> extends never ? never : T>

skipWhile(predicate: (value: T, index: number) => true): OperatorFunction<T, never>

Parameters

predicate

Type: (value: T, index: number) => true.

Returns

OperatorFunction<T, never>

skipWhile(predicate: (value: T, index: number) => boolean): MonoTypeOperatorFunction<T>

Parameters

predicate

Type: (value: T, index: number) => boolean.

Returns

MonoTypeOperatorFunction<T>

See Also

• last
• skip
• skipUntil
• skipLast