JS Practice — Built-in Objects

String.prototype.lastIndexOf() — last occurrence

📖 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()

str.lastIndexOf(searchValue) returns the index of the last occurrence of searchValue, or -1 if not found.

Challenge: Implement findLast(str, sub) using .lastIndexOf().

findLast('abcabc', 'abc') // → 3
findLast('hello', 'l')    // → 3

💡 Hints (1)