every

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

Example 1: Some values false

Example 2: All values true

import { every } from 'rxjs/operators';
import { of } from 'rxjs/observable/of';
//emit 5 values
const allEvens = of(2, 4, 6, 8, 10);
  every(val => val % 2 === 0)
);
//output: true

Additional Resources