Do you know what will be the output of this code? const a = {}; const b = { key: "b" }; const c = { key: "c" }; a[b] = 123; a[c] = 456; console.log(a[b]);

What happens when you use an object as an object key?

Do you know what will be the output of this code?

JavaScript

const a = {};
const b = { key: "b" };
const c = { key: "c" };

a[b] = 123;
a[c] = 456;
console.log(a[b]);

Show answer and explanation

The answer is 456.

Both b and c become the string "[object Object]" when used as keys. The second assignment overwrites the first. Use a Map for object keys.