JS Practice — Built-in Objects

String.prototype.at() — out-of-bounds returns undefined

📖 Usage Example

const str = 'Hello'
str.at(0)    // → 'H'
str.at(-1)   // → 'o'
str.at(1)    // → 'e'

Use at() to access a character by index, supporting negative indices to count from the end.

String.prototype.at() — Out-of-Bounds

Both positive out-of-bounds and very negative indices return undefined.

Challenge: Implement safeAt(str, i) that uses .at(i) and returns '?' if the result is undefined.

safeAt('hi', 0)  // → 'h'
safeAt('hi', 99) // → '?'

💡 Hints (1)