JavaScript Reflect
Last Updated :
11 Apr, 2023
JavaScript Reflect is a built-in object that gives access to other elements for interceptable operations. This object can be used to check whether an object has a particular property or to change or add new properties to an existing object. This object cannot be explicitly created using the new keyword and we cannot call it a function. Reflect has a set of static functions to perform operations.
Syntax:
Reflect.staticFunc()
Parameters: This object does not have fix parameters, it depends upon the static function being used with it
Return Type: The return values depend on the function being used.
Example 1: This example uses Reflect method to check and add properties in a particular object.
Javascript
var details = {
name: "Raj",
course: "DSA",
website: "geeksforgeeks.org",
}
console.log(Reflect.has(details, "course"))
Reflect.set(details, "Rating", "5");
console.log(details)
|
Output:
true
{name: 'Raj', course: 'DSA', website: 'geeksforgeeks.org', Rating: '5'}
Example 2: This example uses Reflect functions to construct a new object.
Javascript
class Details {
constructor(name, course) {
this.name = name;
this.course = course;
}
get fullDetails() {
return `${this.name} ${this.course}`;
}
}
var person = ["Shobhit", "DSA"]
var enroll = Reflect.construct(
Details,
person
);
console.log(enroll instanceof Details);
console.log(enroll);
|
Output:
true
Details {name: 'Shobhit', course: 'DSA'}
Example 3: This example uses Reflect methods to freeze an array so that new elements cannot be added to it.
Javascript
var arr = [];
Reflect.set(arr, 0, "Hello");
Reflect.set(arr, 1, "Welcome");
Reflect.set(arr, 2, "to");
Reflect.set(arr, 3, "GeeksforGeeks");
console.log(arr);
console.log(Reflect.isExtensible(arr))
Reflect.preventExtensions(arr);
Reflect.set(arr, 4, "DSA");
console.log(arr)
|
Output: Using the preventExtensions method new properties cannot be added to the array. This helps to freeze the array
(4) ['Hello', 'Welcome', 'to', 'GeeksforGeeks']
true
(4) ['Hello', 'Welcome', 'to', 'GeeksforGeeks']
Supported Browsers:
- Chrome
- Edge
- Firefox
- Opera
- Safari
We have a complete list of JavaScript Reflect methods, to check please go through the JavaScript Reflect Reference article.
