Using Object.preventExtensions ensures that no new properties can be added to an object, effectively blocking any future extensions to the object. This action is irreversible, as once an object is rendered non-extensible, it cannot be reverted back to an extensible state.
Syntax:
Example
Object.preventExtensions(obj)
Parameter:
obj: This is the object that needs to be made non-extensible.
Return value:
It returns the object being made non-extensible.
Browser Support:
| Chrome | 6 |
|---|---|
Edge |
Yes |
| Firefox | 4 |
| Opera | 12 |
Example 1
Example
const uu = {};
Object.preventExtensions(uu);
console.log(
Object.isExtensible(uu)
);
Output:
Example 2
Example
const obj = {};
Object.preventExtensions(obj);
obj.o = 3;
console.log(
obj.hasOwnProperty("o")
);
Output:
Example 3
Example
const t = {"p":3};
Object.preventExtensions(t);
delete t.p;
console.log ( t.hasOwnProperty ( "p" ) );
//expected output: false
Output:
