JavaScript handler setPrototypeOf() Method

by Online Tutorials Library July 22, 2022

JavaScript handler.setPrototypeOf() Method

The handler.setPrototypeOf method returns a Boolean value true if [[Prototype]] was successfully changed. Otherwise, it will return false. It is a trap for Object.setPrototypeOf().

Syntax

Parameters

target: The target object.

prototype: The object’s new prototype or null.

Return value

Return a Boolean type value.

Browser Support

Chrome	Compatibility unknown
Edge	Compatibility unknown
Firefox	49
Opera	Compatibility unknown

Example 1

  <script>  var pro = { f:13}  var proxy = new Proxy(pro, {    setPrototypeOf(target, newProto) {   return newPrototype in target;    }  });  document.writeln(‘f’ in proxy);  //expected output: true  </script>  

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Output:

true

Example 2

  <script>  var soo={    foo:1  }  var proxy = new Proxy(soo, {    setPrototypeOf(target, newProto) {         }  });  document.writeln(‘a’ in proxy);   //expected output: false  </script>  

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Output:

false

Example 3

  <script>  var xyz = new Proxy({},  {    setPrototypeOf(target, newProto) {      if(key == “a”) return true;        return ;false      }    }  )  var first= (“f” in xyz)  var last = (“g” in xyz)  document.write(“”+first)  //expected output:false  document.write(‘<br>‘);  document.write(“” +last)  //expected output: false  </script>  

Test it Now

Output:

false  false

Next TopicJavaScript handler

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JavaScript handler setPrototypeOf() Method

JavaScript handler.setPrototypeOf() Method

Syntax

Parameters

Return value

Browser Support

Example 1

Example 2

Example 3

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