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My friend Nicholas Zakas made an interesting observation on Mastodon this week: the Array.prototype.every() method always returns true for an empty array.
let arr = []; // Returns true arr.every(function (item) { return false; }); // Also returns true arr.every(function (item) { return true; }); Axel Rauschmayer provided an interesting explanation…
.every()implements universal quantification ("for all", ∀). And that operator is always true for empty sets…That is also how we understand [for all] intuitively if we use it in natural language: "All humans that live on Venus have blue skin" is true (because no humans live on Venus).
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Cheers,
Chris
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