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every
signature: every(predicate: function, thisArg: any): Observable
every(predicate: function, thisArg: any): ObservableIf all values pass predicate before completion emit true, else false.
Examples
Example 1: Some values false
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// RxJS v6+
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import { every } from 'rxjs/operators';
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import { of } from 'rxjs';
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//emit 5 values
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const source = of(1, 2, 3, 4, 5);
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const example = source.pipe(
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//is every value even?
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every(val => val % 2 === 0)
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);
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//output: false
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const subscribe = example.subscribe(val => console.log(val));
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Example 2: All values true
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// RxJS v6+
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import { every } from 'rxjs/operators';
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import { of } from 'rxjs';
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//emit 5 values
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const allEvens = of(2, 4, 6, 8, 10);
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const example = allEvens.pipe(
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//is every value even?
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every(val => val % 2 === 0)
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);
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//output: true
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const subscribe = example.subscribe(val => console.log(val));
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Example 3: Values arriving over time and completing stream prematurely due to every returning false
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// RxJS v6+
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console.clear();
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import { concat, of } from 'rxjs';
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import { every, delay, tap } from 'rxjs/operators';
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const log = console.log;
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const returnCode = request => (Number.isInteger(request) ? 200 : 400);
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const fakeRequest = request =>
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of({ code: returnCode(request) }).pipe(
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tap(_ => log(request)),
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delay(1000)
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);
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const apiCalls$ = concat(
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fakeRequest(1),
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fakeRequest('invalid payload'),
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fakeRequest(2) //this won't execute as every will return false for previous line
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).pipe(
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every(e => e.code === 200),
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tap(e => log(`all request successful: ${e}`))
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);
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apiCalls$.subscribe();
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Additional Resources
Last modified 1yr ago