Why .every() on an empty list is true

1 · Vincent Driessen · Dec. 6, 2021, 9:04 a.m.
We can all pretty intuitively understand how .some() and .every() predicate expressions on lists work. Let's define a list of Simpsons: const simpsons = [ { name: 'Homer', age: 39 }, { name: 'Marge', age: 37 }, { name: 'Bart', age: 13 }, { name: 'Lisa', age: 11 }, { name: 'Maggie', age: 4 }, ]; And a predicate to tell if someone is an adult: function isAdult(simpson) { return simpson.age >= 18; } Then, these statements are pretty obvious: simpsons.some(isAdult); // => true, becau...