JS Practice — Built-in Objects

String.prototype.lastIndexOf() — case-sensitive

📖 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() — Case Sensitivity

Like .indexOf(), .lastIndexOf() is case-sensitive.

Challenge: Implement lastIndexIgnoreCase(str, sub) that searches case-insensitively.

lastIndexIgnoreCase('Hello World Hello', 'hello') // → 12

💡 Hints (1)