JS Practice — Built-in Objects

String.prototype.includes() — not found

📖 Usage Example

const str = 'Hello, World!'
str.includes('World')    // → true
str.includes('xyz')      // → false
str.includes('Hello', 1) // → false

Use includes() to check if a string contains a specific substring, with an optional start position.

String.prototype.includes() — Missing Substring

Challenge: Implement lacksDigit(str) that returns true when str does NOT include any digit. Use .includes() for a single digit check.

For simplicity, check for the digit '5'.

lacksDigit('hello') // → true
lacksDigit('h5llo') // → false

💡 Hints (1)