JS Practice — Built-in Objects

Proxy has trap — always false

📖 Usage Example

const p = new Proxy({}, {
  has: (target, key) => key.startsWith('a')
})
console.log('apple' in p)  // → true
console.log('banana' in p) // → false

The has trap intercepts the in operator, allowing you to control which property names are considered present on a proxy.

has trap — hide all properties

When the has trap always returns false, no key ever appears present — even if the target has it.

Challenge: Verify that 'x' in p is false when the has trap always returns false.

💡 Hints (1)

• The `has` trap can lie — returning `false` even if the target has the property.