Shallow vs Deep Copy of Objects in JavaScript

When we need to copy an object to another object, we generally use something like this:

const mainObject = { id: 1 };
const secondaryObject = { ...mainObject };

But this only works for copying the shallow properties of the object. If we have a case like the following code, the scenario changes:

const mainObject = { id: 1, user: { name: 'John Doe', age: 30 } };
const secondaryObject = { ...mainObject };

The property user won't be copied; it will still be related to mainObject. So, if we alter the user property, it will also affect mainObject. To solve this, we can do the following:

const mainObject = { id: 1, user: { name: 'John Doe', age: 30 } };
const deepCopy = JSON.parse(JSON.stringify(mainObject));

Now, we have a deep copy of mainObject, with two distinct memory addresses.