JS Practice — Built-in Objects

String.prototype.lastIndexOf() — multiple occurrences

📖 Usage Example

const str = 'abcabc'
str.lastIndexOf('a')    // → 3
str.lastIndexOf('z')    // → -1
str.lastIndexOf('b', 3) // → 1

Use lastIndexOf() to find the index of the last occurrence of a substring, searching from right to left.

String.prototype.lastIndexOf() — Multiple Occurrences

When there are multiple matches, .lastIndexOf() returns the rightmost one.

Challenge: Implement lastOccurrence(str, ch) using .lastIndexOf().

lastOccurrence('abracadabra', 'a') // → 10

💡 Hints (1)