JS Practice — Built-in Objects

String.prototype.charAt() — out-of-bounds returns empty string

📖 Usage Example

const str = 'Hello'
str.charAt(0)    // → 'H'
str.charAt(1)    // → 'e'
str.charAt(99)   // → ''

Use charAt() to get the character at a specific index, returning an empty string for out-of-bounds positions.

String.prototype.charAt() — Out-of-Bounds

charAt returns '' (empty string) for out-of-bounds, while .at() returns undefined.

Challenge: Implement isOutOfBounds(str, i) that returns true when .charAt(i) returns an empty string.

isOutOfBounds('hi', 99) // → true
isOutOfBounds('hi', 0)  // → false

💡 Hints (1)

• Unlike `.at()`, `.charAt()` does NOT support negative indices — they are treated as 0 or out-of-bounds.