JS Built-ins
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ArrayArray.prototype.findbeginner

Array.prototype.find() — returns undefined when not found

📖 Usage Example
const arr = [1, 2, 3]
arr.find(n => n > 10)  // → undefined  (not found)

find() returns undefined when no element satisfies the predicate — check for this case.

Array.prototype.find() — no match

When no element satisfies the predicate, find() returns undefined (not -1 like indexOf).

Challenge: Implement findEven(nums) that returns the first even number, or undefined if none exists.

findEven([1, 3, 4, 5]) // → 4
findEven([1, 3, 5])    // → undefined
💡 Hints (2)
  • • `find()` returns `undefined`, not `-1` — check carefully in conditionals.
  • • To test the return value, use `=== undefined` or the optional chaining operator.