JavaScript handler isExtensible() Method

by Online Tutorials Library July 22, 2022

JavaScript handler.isExtensible() Method

The handler.isExtensible() method a trap for Object.isExtensible(). We can be mostly used for logging or auditing calls to Object.isExtensible (determine if an object is “extensible”).

Syntax

Parameters

target: The target object.

Return value

Return a Boolean value.

Browser Support

Chrome	Compatibility unknown
Edge	Compatibility unknown
Firefox	31
Opera	Compatibility unknown

Example 1

  var x = { foo: 1 };  var proxy = new Proxy(x, {    isExtensible: function(target) {      document.writeln(‘in isExtensible’);      //expected output: in isExtensible    return Object.isExtensible(target);    }  });  document.writeln(Object.isExtensible(proxy));  //expected output: true   document.writeln(“<br>“)  Object.preventExtensions(proxy);  document.writeln(Object.isExtensible(proxy));    //expected output: false  

Test it Now

Output:

in isExtensible true   in isExtensible false

Example 2

  const pro={  too:1 }  const  proxy = new Proxy(pro, {    isExtensible: function(target) {      document.writeln(‘ in value : ‘);      return true;    }  });    document.writeln(Object.isExtensible(proxy));  //expected output: in value : true  

Test it Now

Output:

in value : true

Example 3

  var a = {    canEvolve: true  };  var b = {     isExtensible(target) {      return true;    },     };  const proxy1 = new Proxy(a, b);  document.writeln(Object.isExtensible(proxy1));  // expected output: true  

Test it Now

Output:

true

Next TopicJavaScript handler

apply()construct()defineProperty()deleteProperty()get isExtensible()javascript handler javascript methods javascript tutorial ownKeys()set setPrototypeOf()

JavaScript handler isExtensible() Method

JavaScript handler.isExtensible() Method

Syntax

Parameters

Return value

Browser Support

Example 1

Example 2

Example 3

Working of HashSet in Java

JavaScript Array concat() Method

You may also like