JavaScript Handler defineProperty() Method

JavaScript handler.defineProperty() method in Javascript is used to define the new properties and to modify the existing properties directly on an object. It is a trap for Object.defineProper().

Syntax: 

const p = new Proxy(target, {
 defineProperty: function(target, property, descriptor) {
 }
}); 

Parameters: This method accepts three parameters as mentioned above and described below: 

• Target: This parameter holds the target object.
• property: This parameter is the name or Symbol of the property whose description is going to be retrieved..
• descriptor: This parameter is the descriptor for the property being defined or modified.

Return value: This method returns a Boolean value which is used to indicate if the property is successfully defined.

Below example illustrates the handler.defineProperty() method in JavaScript:

Example 1: In this example, we will see the use of the handler.defineProperty() method in JavaScript.

Output: 

"Type : String"
"in defineProperty"

Example 2: In this example, we will see the use of the handler.defineProperty() method in JavaScript.

Output:

Error: Invalid attempt to define private "_propt" property

Supported Browsers: The browsers supported by handler.defineProperty() method are listed below: 

• Google Chrome 49 and above
• Firefox 18 and above
• Opera 36 and above
• Safari 10 and above
• Edge 12 and above

We have a complete list of Javascript Proxy/handler methods, to check those go through the Javascript Proxy/handler Reference article.