Interview: custom operator onlyAdmins()

Build a custom operator that keeps admins and returns their names.

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const { from, filter, map } = Rx;

function onlyAdmins() {
  return source$ => source$.pipe(
    filter(user => user.role === 'admin'),
    map(user => user.name)
  );
}

const users$ = from([
  { name: 'Ada', role: 'admin' },
  { name: 'Lin', role: 'user' },
]);

users$.pipe(onlyAdmins()).subscribe(value => console.log(value));

script.ts // TypeScript

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