Object.freeze() vs Object.seal() vs Object.preventExtensions()

index.js

let obj = {id: 1, name: "John Doe", age: 25};


/**
 * Object.freeze()
 * 
 * In freeze object, addition, updation and delete operation cannot be done except read
 * 
 */

Object.freeze(obj);

// update the existing property value
obj.age = 23;

// adding new property
obj.gender = "male";

// deleting name property
console.log(delete obj.name); // false

console.log(obj); // {id: 1, name: "John Doe", age: 25}


/**
 * Object.seal()
 * 
 * In sealed object, addition and deletion cannot be done except updation and read
 * 
 */

Object.seal(obj);

// update the existing property value
obj.age = 23;

// adding new property
obj.gender = "male";

// deleting name property
console.log(delete obj.name); // false

console.log(obj); // {id: 1, name: "John Doe", age: 23}


/**
 * Object.preventExtensions()
 * 
 * In prevent extension object, addition cannot be done except updation, deletion and read
 * 
 */

Object.preventExtensions(obj);

// update the existing property value
obj.age = 23;

// adding new property
obj.gender = "male";

// deleting name property
console.log(delete obj.name); // true

console.log(obj); // {id: 1, age: 23}