handler.deleteProperty()

The following parameters are passed to the deleteProperty() method. this is bound to the handler.

target

The target object.

property

The name or Symbol of the property to delete.

The deleteProperty() method must return a Boolean indicating whether or not the property has been successfully deleted.

The handler.deleteProperty() method is a trap for the delete operator.

This trap can intercept these operations:

• Property deletion: delete proxy[foo] and delete proxy.foo
• Reflect.deleteProperty()

If the following invariants are violated, the proxy will throw a TypeError:

• A property cannot be deleted, if it exists as a non-configurable own property of the target object.

The following code traps the delete operator.

const p = new Proxy({}, {
  deleteProperty: function(target, prop) {
    if (prop in target){
      delete target[prop]
      console.log('property removed: ' + prop)
      return true
    }
    else {
      console.log('property not found: ' + prop)
      return false
    }
  }
})

let result

p.a = 10
console.log('a' in p)  // true

result = delete p.a    // "property removed: a"
console.log(result)    // true
console.log('a' in p)  // false

result = delete p.a    // "property not found: a"
console.log(result)    // false

• Proxy
• handler
• delete operator
• Reflect.deleteProperty()