Last Updated : 12 Jul, 2025
JavaScript handler.set() method in JavaScript is a trap for setting a property value. This method returns a boolean value.
Syntax:
const p = new Proxy(target, {
set: function(target, property, value, receiver) {
}
});
Parameters: This method accepts four parameters as mentioned above and described below:
Return value: This method always returns a boolean value.
Below examples illustrate the handler.set() Method in JavaScript:
Example 1: In this example, we will see the basic use of the handler.set() Method in JavaScript.
javascript
function gfg() {
this.users = "Millions";
}
const handler1 = {
set(obj, prop, value) {
if ((prop === 'users') && ((value % 2) !== 0)) {
console.log('GEEKSFORGEEKS : Computer Science Portal');
} else {
return Reflect.set(...arguments);
}
}
};
const gfg1 = new gfg();
const proxy1 = new Proxy(gfg1, handler1);
proxy1.users = 1;
console.log(proxy1.users);
Output:
"GEEKSFORGEEKS : Computer Science Portal" "Millions"
Example 2: In this example, we will see the basic use of the handler.set() Method in JavaScript.
javascript
const p = new Proxy({}, {
set: function (target, prop, value, receiver) {
target[prop] = value;
console.log('property set: ' + prop + ' = ' + value);
return true;
}
})
console.log('a' in p);
p.a = 10;
console.log('a' in p);
console.log(p.a);
let x = { foo: 1 };
let proxy = new Proxy(x, {
set: function (target, name, value, proxy) {
target[name] = value + " --> " + value.toUpperCase();
}
});
proxy.foo = 'geeksforgeeks';
console.log(x.foo);
Output:
false "property set: a = 10" true 10 "geeksforgeeks --> GEEKSFORGEEKS"
Supported Browsers: The browsers supported by handler.set() method are listed below.
We have a complete list of Javascript Proxy/handler methods, to check those go through the Javascript Proxy/handler Reference article.
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