isSealed

The isSealed function checks if an object is sealed, meaning new properties cannot be added and existing ones cannot be removed.

Syntax

isSealed(obj): boolean

Parameters

Name	Type	Description
obj	object	Object to be checked.

Return

Type	Description
boolean	Returns true if the object is sealed, otherwise false.

Examples

const obj = Object.seal({ a: 1 });
isSealed(obj); // true
isSealed({ b: 2 }); // false

Notes

• Internally uses Object.isSealed.
• Sealed objects cannot have properties added or removed, but existing property values can still be changed.

References

• MDN: Object.isSealed()