handler.get()

The handler.get() method is a trap for getting a property value.

const p = new Proxy(target, {
  get: function(target, property, receiver) {
  }
});

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

target

The target object.

property

The name or Symbol  of the property to get. 

receiver

Either the proxy or an object that inherits from the proxy.

The get() method can return any value.

The handler.get() method is a trap for getting a property value.

This trap can intercept these operations:

• Property access: proxy[foo]and proxy.bar
• Inherited property access: Object.create(proxy)[foo]
• Reflect.get()

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

• The value reported for a property must be the same as the value of the corresponding target object property if the target object property is a non-writable, non-configurable own data property.
• The value reported for a property must be undefined if the corresponding target object property is a non-configurable own accessor property that has undefined as its [[Get]] attribute.

The following code traps getting a property value.

const p = new Proxy({}, {
  get: function(target, property, receiver) {
    console.log('called: ' + property);
    return 10;
  }
});

console.log(p.a); // "called: a"
                  // 10

The following code violates an invariant.

const obj = {};
Object.defineProperty(obj, 'a', {
  configurable: false,
  enumerable: false,
  value: 10,
  writable: false
});

const p = new Proxy(obj, {
  get: function(target, property) {
    return 20;
  }
});

p.a; // TypeError is thrown

• Proxy
• handler
• Reflect.get()