JS Practice — Built-in Objects

String.prototype.substring() — start === end returns empty string

📖 Usage Example

const str = 'Hello, World!'
str.substring(7, 12)   // → 'World'
str.substring(5, 2)    // → 'llo' (args swapped)
str.substring(7)       // → 'World!'

Use substring() to extract characters between two indices, automatically swapping them if start is greater than end.

String.prototype.substring() — Same Indices

When start === end, .substring() returns an empty string.

Challenge: Implement emptySubstring(str, n) that calls substring(n, n).

emptySubstring('hello', 2) // → ''

💡 Hints (1)