JS - What is output Question 5

Understanding Object Assignment in JavaScript

Let's explore how object assignment works in JavaScript using the following example:

let c = { greeting: 'Hey!' };
let d;

d = c;
c.greeting = 'Hello';
console.log(d.greeting);

What do you think the output of console.log(d.greeting) would be?

The output would be:

Hello

Let's understand why:

1. let c = { greeting: 'Hey!' };: This line declares a variable c and assigns it an object with a greeting property set to 'Hey!'.

2. let d;: This line declares a variable d but doesn't assign it any value yet.

3. d = c;: Here, d is assigned the same object that c is referencing. Both c and d now point to the same object in memory.

4. c.greeting = 'Hello';: This line modifies the greeting property of the object referenced by c to 'Hello'.

5. console.log(d.greeting);: Since d points to the same object as c, accessing the greeting property of d also reflects the change made to the object through c. Thus, the output is 'Hello'.

This demonstrates how object assignment works in JavaScript, where variables pointing to objects reference the same underlying object in memory.