JavaScript handler set() Method

by Online Tutorials Library July 22, 2022

JavaScripthand handler.set() Method

The handler.set method is an assignment of a value to a property value. The set can be iterator in the insertion order. It is a collection of items which are unique. If an assignment succeeded, then return true. Otherwise, returns false.

An Iterator is an object which defines a sequence and potentially a return value upon its termination.

Syntax

Parameters

target: The target object.

property: Name or Symbol of the property.

value: New value of the property.

receiver: This is usually the proxy itself. A set handler assignment indirectly, via the prototype chain or various other ways.

Return value

Return a Boolean value.

Browser Support

Chrome	49
Edge	12
Firefox	18
Opera	36

Example 1

  <script>  var proxy = { “a”: 1, “b”: 2 }  var pset = new Proxy(    proxy, {      set: function(y, idx, value) {      y[idx] = value * 10     }    }  )  pset.c = 3  for(var z in pset) {    document.writeln(z + “=” )    // print equal sign.    document.writeln(pset[z])        //expected output: a= 1 b= 2 c= 30  }  </script>  

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Output:

a= 1 b= 2 c= 30

Example 2

  <script>  var x = { foo: 1 };  var proxy = new Proxy(x, {    set: function(target, name, value, proxy) {    document.writeln (‘in set’);  target[name] = value.toUpperCase();    }  });  proxy.foo = ‘proxy method’;  document.writeln(x.foo); // value stored on x is uppercase   //expected output: in set PROXY METHOD   </script>  

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Output:

in set PROXY METHOD

Example 3

  <script>  const q={   foo:1  }  const p = new Proxy(q, {    set: function(target, prop, value, receiver) {      target[prop] = value;      document.writeln(‘property set: ‘ + prop + ‘ = ‘ + value);      //expected output: property set: a = 10      }  })  document.writeln(‘a’ in p);   //expected output: false  p.a = 10;    // “property set: a = 10”  </script>  

Test it Now

Output:

false property set: a = 10

Next TopicJavaScript handler

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JavaScript handler set() Method

JavaScripthand handler.set() Method

Syntax

Parameters

Return value

Browser Support

Example 1

Example 2

Example 3

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