JavaScript Object.seal() Method

The Object.seal() method of JavaScript seals an object which prevents new properties from being added to it and marks all existing properties as non-configurable. The object to be sealed is passed as an argument, and the method returns the object which has been sealed.

Syntax:

Parameter:

obj: It is the object which should be sealed.

Return value:

The Object.sealed() method returns the object which has been sealed.

Browser Support:

Chrome	6
Edge	Yes
Firefox	4
Opera	12

Example 1

const obj1 = { property1: 'Marry'};
        const obj2 = Object.seal(obj1);
       // prevents other code from deleting properties of an object.
        obj2.property1 = 'carry';
        console.log(obj2.property1);

Output:

"carry"

Example 2

 const object1 = {
  property1: 29
};
Object.seal(object1);
// Prevents other code from deleting properties of an object.
object1.property1 =45;
console.log(object1.property1);
delete object1.property1;
   // cannot delete when sealed

Output:

Example 3

const object1 = {
  property1: 42
};
Object.seal(object1);
object1.property1 = 45;
console.log(object1.property1);

delete object1.property1; // cannot delete when sealed
console.log(object1.property1);

const object2 = {
  property2: 45};
object2.property2 =67;
console.log(object2.property2);

Output: