• Shallow Copy: A copy of an object or array where only the top-level elements are copied. Nested objects or arrays are still linked to the original.
• Deep Copy: A copy of an object or array where all elements, including nested objects or arrays, are copied, so the original and the copy are completely separate.

1. Shallow Copy Example (Array)

A shallow copy means that only the top-level values (elements) are copied. If the array contains other arrays or objects inside it, the copy will still point to the same inner array or object.

Example of Shallow Copy:

let originalArray = [1, 2, [3, 4]];

// Creating a shallow copy using the spread operator
let shallowCopy = [...originalArray];

// Changing the inner array in the shallow copy
shallowCopy[2][0] = 99;

console.log(originalArray[2][0]);  // Output: 99 (original array is also affected)
console.log(shallowCopy[2][0]);    // Output: 99 (shallow copy is affected)

Explanation:

• Both originalArray and shallowCopy point to the same inner array [3, 4].
• So when we change shallowCopy[2][0] to 99, it also changes originalArray[2][0], because both share the same inner array.

2. Deep Copy Example (Object)

A deep copy means that both the top-level and inner values (like objects or arrays inside the object) are copied. They are completely separate, so changes in the copy do not affect the original.

Example of Deep Copy:

let originalObject = {
  name: 'Shubhadip',
  address: { city: 'Kolkata', zip: 700001 }
};

// Creating a deep copy using JSON methods
let deepCopy = JSON.parse(JSON.stringify(originalObject));

// Changing the inner object in the deep copy
deepCopy.address.city = 'Mumbai';

console.log(originalObject.address.city);  // Output: 'Kolkata' (original is not affected)
console.log(deepCopy.address.city);        // Output: 'Mumbai' (deep copy is changed)

Explanation:

• originalObject and deepCopy are completely separate.
• Changing deepCopy.address.city to 'Mumbai' does not change originalObject.address.city, because they are different objects in memory.

Summary: