JS Practice — Built-in Objects

Array.prototype.every() — vacuous truth

📖 Usage Example

const empty = []
empty.every(x => x > 0)  // → true  (vacuous truth)

every() returns true for empty arrays — there are no elements to violate the condition.

Array.prototype.every() — empty arrays

By mathematical convention, [].every(anything) always returns true. This is called vacuous truth — there are no elements to violate the condition.

Challenge: Implement isEveryLong(strs) that returns true if every string has length > 5. Observe that an empty array returns true.

isEveryLong(['hello world', 'goodbye']) // → true
isEveryLong(['hi'])                     // → false
isEveryLong([])                         // → true

💡 Hints (2)

• This is intentional JavaScript behavior — `[].every()` always returns `true`.
• Think of it as: "there are no elements that fail the condition".