JavaScript: Create | Read | Update | Delete Operations - freeze(), seal(), preventExtensions()

Object.freeze():-

This method freezes the object which means new properties cannot be added, existing properties cannot be removed or modified. The enumerability, configurability or writability of existing properties is prohibited. It returns the same object (does not create a copy) that was passed into the function. Also, the frozen object is immutable (not necessarily constant).

Syntax

Object.freeze(obj)

Have you heard about Shallow Freeze? When you call the method Object.freeze() on an object, the freeze rules are applicable only to the immediate properties of object which implies if the values of these properties are object themselves those objects are not bound by any rules and are not frozen.

Object.seal():-

This method seals the object which means it allows to change existing properties but new properties cannot be added to it. Also, all existing properties are marked as non-configurable. But it does not prevent the value of data properties from being changed. The __proto__ property is sealed too.

Syntax

Object.seal(obj)

Object.preventExtensions():-

This method makes the object non-extensible i.e. new properties can never be added to an object. This process is irreversible i.e. if an object is marked as non-extensible, it cannot be reversed. However, properties can still be added to the object prototype.

Syntax

Object.preventExtensions(obj)

Happy Learning!