output of the following program

What will be the output of the following program?

var z = {};
var x = { id: 10 };
y = { id: 20 };

z[x] = 'Anil'
z[y] = 'Singh'


Answer is  -

 In Detailed Explanation:

Because you are adding an object key to the z object. So when you do z[x] = 'Anil' the z object becomes

z: {
[object object]: 'Anil'

KEEP IN MIND: When you use objects as keys the key will be [object object]. So when you do z[y] it overrides the key "[object object]" with 'Singh'.

So in the end the object z has a key "[object object]" and a value 'Singh'.

Finally, when you do console.log you log twice the key. With what in mind, if you create another object another = {hello: ‘world’} and you console.log (z[another]) you will again get ''Singh".

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