every

signature: every(predicate: function, thisArg: any): Observable

If all values pass predicate before completion emit true, else false.

Examples

Example 1: Some values false

( Stackblitz | jsBin | jsFiddle )

// RxJS v6+
import { every } from 'rxjs/operators';
import { of } from 'rxjs';

//emit 5 values
const source = of(1, 2, 3, 4, 5);
const example = source.pipe(
  //is every value even?
  every(val => val % 2 === 0)
);
//output: false
const subscribe = example.subscribe(val => console.log(val));
Example 2: All values true

( Stackblitz | jsBin | jsFiddle )

// RxJS v6+
import { every } from 'rxjs/operators';
import { of } from 'rxjs';

//emit 5 values
const allEvens = of(2, 4, 6, 8, 10);
const example = allEvens.pipe(
  //is every value even?
  every(val => val % 2 === 0)
);
//output: true
const subscribe = example.subscribe(val => console.log(val));
Example 3: Values arriving over time and completing stream prematurely due to every returning false

( Stackblitz )

// RxJS v6+
console.clear();
import { concat, of } from 'rxjs';
import { every, delay, tap } from 'rxjs/operators';

const log = console.log;
const returnCode = request => (Number.isInteger(request) ? 200 : 400);
const fakeRequest = request =>
  of({ code: returnCode(request) }).pipe(
    tap(_ => log(request)),
    delay(1000)
  );

const apiCalls$ = concat(
  fakeRequest(1),
  fakeRequest('invalid payload'),
  fakeRequest(2) //this won't execute as every will return false for previous line
).pipe(
  every(e => e.code === 200),
  tap(e => log(`all request successful: ${e}`))
);

apiCalls$.subscribe();

Additional Resources


:file_folder: Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/every.ts

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