JS Practice — Built-in Objects

Function.prototype.call() — borrow Array.push

📖 Usage Example

function Point(x, y) { this.x = x; this.y = y }
const p = {}
Point.call(p, 1, 2)
p  // → { x: 1, y: 2 }

call() is used to invoke a constructor function on an existing object.

Borrowing array methods with call()

You can borrow built-in array methods for array-like objects using call().

Challenge: Use [].push.call(arr, 10) to push 10 onto arr and verify arr[0] === 10.

💡 Hints (1)