JavaScript Demo: Object.prototype.seal()

const object1 = {
  property1: 42
};

Object.seal(object1);
object1.property1 = 33;
console.log(object1.property1);
// expected output: 33

delete object1.property1; // cannot delete when sealed
console.log(object1.property1);
// expected output: 33

JavaScript Demo: Object.prototype.seal()

​x
const object1 = {
  property1: 42
};
​
Object.seal(object1);
object1.property1 = 33;
console.log(object1.property1);
// expected output: 33
​
delete object1.property1; // cannot delete when sealed
console.log(object1.property1);
// expected output: 33
​