JS Practice — Built-in Objects

Array.prototype.includes() — check for a value

📖 Usage Example

const fruits = ['apple', 'banana', 'cherry']
fruits.includes('banana')  // → true
fruits.includes('grape')   // → false

Use includes() to check whether a specific value exists in an array.

Array.prototype.includes()

Array.prototype.includes(value, fromIndex?) returns true if the array contains value, using the SameValueZero algorithm (like === but also handles NaN).

Challenge: Implement hasValue(arr, val) that returns arr.includes(val).

hasValue([1, 2, 3], 2) // → true
hasValue([1, 2, 3], 5) // → false

💡 Hints (2)

• `includes()` returns a boolean — true or false.
• It uses SameValueZero comparison, similar to `===`, but also handles `NaN`.