JavaScript · Middle · Question 74 of 75

What does this code print?

const obj = {};
const a = { id: 1 }, b = { id: 2 };
obj[a] = "first";
obj[b] = "second";
console.log(obj[a]);

✓Correct answer: "second"
2"first"
3undefined

Explanation

Object keys are strings (or symbols); both objects become "[object Object]", so the second write overwrites the first. Use a Map for object keys.

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