The **`Object.isSealed()` method** determines if an object is sealed or not. An object is sealed if:
*  The object is not extensible.
* Its properties are non-configurable.

> **Note**: 
> * An object is sealed using the `Object.seal()` or `Object.freeze()` methods.
> * A sealed object cannot be unsealed.

# Declaration
The `isSealed()` method is declared as follows:
```js
Object.isSealed(obj)
```
* **`obj`**: The object that is to be checked to determine whether it is sealed.

> Note: If `obj` is not an object, `TypeError` is thrown.

# Return value
The `isSealed()` method returns a boolean value depending on whether or not the object `obj` is sealed.
* **`true`**: if `obj` is sealed.
* **`false`**: if `obj` is not sealed.





# Code
Consider the code snippet below, which demonstrates the use of the `isSealed()` function.


var obj = { property1:'Foo'}

console.log("obj is sealed: ", Object.isSealed(obj))

Object.seal(obj)

console.log("obj is sealed: ", Object.isSealed(obj))

# Explanation
An object `obj` is created in *line 1*. Calling the `isSealed()` method on `obj` returns `false`, as the object is not sealed. After `obj` is sealed in *line 5*, the `isSealed()` method returns `true`.

What is Object.isSealed() in JavaScript?

Declaration

Return value

Code

Explanation