JavaScript handler ownKeys() Method

by Online Tutorials Library July 22, 2022

JavaScript handler.ownKeys() Method

The handler.ownKeys() method of JavaScript is used to return an enumerable object. This method is a trap for Reflect.ownKeys().

Syntax

Parameters

target: The target object.

Return value

Return an enumerable object.

Browser Support

Chrome	49
Edge	12
Firefox	18
Opera	36

Example 1

  <script>  var proxy1 = new Proxy({}, {    ownKeys: function(target) {     document.writeln(” Use handler.ownKeys() is “);      return [‘a’, ‘b’, ‘c’];    }  });  document.writeln(Object.getOwnPropertyNames(proxy1));   //expected output: Use handler.ownKeys() is a,b,c  </script>  

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Output:

Use handler.ownKeys() is a,b,c

Example 2

  <script>  var x = {   Age:24,   Count: 45  }  var y = {    ownKeys (target) {      return Reflect.ownKeys(target)    }  }  var z = new Proxy(x,y);  for (let key of Object.keys(z))   {    document.writeln(key);    // expected output: Age Count   }  </script>  

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Output:

Age Count

Example 3

  <script>  var x = { foo: 1 };  Object.defineProperty(x, ‘variable’, { value: 2,                                     writable: true,                                  enumerable: false,                                    configurable: true } );    var proxy = new Proxy(x, {    ownKeys: function(target, a, b) {      document.writeln(‘in ownKeys method’);  var names = Object.getOwnPropertyNames(target);      //Useing Object.getOwnProperty mehod.      var symbols = Object.getOwnPropertySymbols(target);      return names.concat(symbols);    }  });  document.writeln(Object.keys(proxy));  //expected.output: in ownKeys method foo   document.writeln(“<br>“)  document.writeln(Object.getOwnPropertyNames(proxy));  //expected output: in ownKeys method foo,variable  </script>  

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Output:

in ownKeys method foo   in ownKeys method foo,variable

Next TopicJavaScript handler

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JavaScript handler ownKeys() Method

JavaScript handler.ownKeys() Method

Syntax

Parameters

Return value

Browser Support

Example 1

Example 2

Example 3

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