JavaScript Object isSealed() Method

JavaScript object.isSealed() method is used to determine if an object is sealed or not. An object is sealed if all of the below-mentioned conditions hold true :

• If it is not extensible.
• If all of its properties are non-configurable.
• If it is not removable (but not necessarily non-writable).

Object.isSealed() takes the object as an argument that has to be checked and returns a boolean representing whether the object is sealed or not. 

Syntax:

Object.isSealed(obj)

Parameters: 

• obj: It is the object which has to be checked. 

Return Value: Object.isSealed() returns a boolean representing whether the object is sealed or not.

Examples of the above function are provided below. 

Example 1: In the above example the object has not been sealed using the Object.seal() method, therefore, it returns false when it is checked using Object.isSealed() method.

// creating an object constructor
// and assigning values to it
const object = {
    property: 'hi geeksforgeeks'
};

// checking whether the object
// is sealed or not
console.log(Object.isSealed(object));

Output:

false

Example 2: In the above example the object has been sealed using the Object.seal() method, therefore, it returns true when it is checked using Object.isSealed() method.

// creating an object constructor
// and assigning values to it
const object = {
    property: 'hi geeksforgeeks'
};

// Using seal() method to seal the object
Object.seal(object);

// checking whether the
// object is frozen or not
console.log(Object.isSealed(object));

Output:

true

Applications:

• Object.isSealed() is used for checking whether an object is sealed or not.

Exceptions :

• It causes a TypeError if the argument passed is not an object.
• If an object is not passed as an argument to the method, then it treats it as a sealed object and returns true.

We have a complete list of Javascript Object methods, to check those please go through this JavaScript Object Complete Reference article.

Supported Browsers:

• Chrome 6 and above
• Edge 12 and above
• Firefox 4 and above
• Internet Explorer 9 and above
• Opera 12 and above
• Safari 5.1 and above