JavaScript | handler.ownKeys() Method

The handler.ownKeys() method in JavaScript is a trap for Reflect.ownKeys() method and this method returns an enumerable object.
Syntax:

const p = new Proxy(target, {
  ownKeys: function(target) {
  }
});

Parameters: This method accepts a single parameter as mentioned above and described below: 

• target: This parameter holds the target object.

Return value: This method always return an enumerable object.
Below examples illustrate the handler.ownKeys() method in JavaScript:
Example 1:

javascript

const monster1 = {
  prop1: 253,
  prop2: "Geeks",
  prop3: 0101011
}

const handler1 = {
  ownKeys (target) {
    return Reflect.ownKeys(target)
  }
}

const proxy = new Proxy(monster1, handler1);

for (let key of Object.keys(proxy)) {
  document.writeln(key+"<br>");
}

Output:

prop1
prop2
prop3

Example 2:

javascript

var proxy1 = new Proxy({}, {
  ownKeys: function(target) {
   document.writeln(" <br> handler.ownKeys() Method <br> <br>");
    return ['Geeks1', 'Geeks2', 'Geeks3'];
  }
});
document.writeln(Object.getOwnPropertyNames(proxy1));

Output:

handler.ownKeys() Method

Geeks1,Geeks2,Geeks3

Supported Browsers: The browsers supported by handler.ownKeys() method are listed below: 

• Google Chrome 49 and above
• Edge 12 and above
• Firefox 18 and above
• Opera 36 and above
• Safari 10 and above

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