JS Practice — Built-in Objects

String.prototype.charCodeAt() — detect digit character

📖 Usage Example

const str = 'ABC'
str.charCodeAt(0)   // → 65
str.charCodeAt(1)   // → 66
str.charCodeAt(99)  // → NaN

Use charCodeAt() to get the UTF-16 code unit value of the character at the given index.

String.prototype.charCodeAt() — Digit Detection

Digit characters '0'–'9' have char codes 48–57.

Challenge: Implement isDigitChar(ch) using .charCodeAt(0) to detect digit characters.

isDigitChar('5') // → true
isDigitChar('a') // → false

💡 Hints (1)