JS Built-ins
← String39 / 195
StringString.prototype.codePointAtbeginner

String.prototype.codePointAt() — undefined for out-of-bounds

📖 Usage Example
const str = 'Hello'
str.codePointAt(0)     // → 72
'😀'.codePointAt(0)    // → 128512

Use codePointAt() to get the full Unicode code point at a position, correctly handling supplementary characters.

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

Like .at(), .codePointAt() returns undefined when the index is out of range.

Challenge: Implement isValidPos(str, pos) that returns true when str.codePointAt(pos) is not undefined.

isValidPos('hi', 0) // → true
isValidPos('hi', 5) // → false
💡 Hints (1)
  • • `.codePointAt()` returns `undefined` for out-of-range indices.