10 Tricky JavaScript Questions and Answers 🤯

JavaScript can sometimes behave in unexpected ways. Below are 10 tricky questions with detailed explanations that will help you better understand the quirks of the language.

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1. What will the following output?

console.log(0.1 + 0.2 === 0.3);

Answer: false
Explanation:
In JavaScript (and most programming languages), floating-point arithmetic isn’t always precise.
0.1 + 0.2 results in 0.30000000000000004, not exactly 0.3.

2. What’s the output?

console.log([] + []);
console.log([] + {});
console.log({} + []);

Answer:

""
"[object Object]"
0

Explanation:

• [] + [] returns an empty string because JavaScript converts arrays to strings during concatenation.
• [] + {} becomes "[object Object]" because {} is converted to its string representation.
• {} when placed at the beginning of a line is interpreted as a block, so {} + [] returns 0.

3. What will this code log?

console.log(typeof null);

Answer: "object"
Explanation:
This is a well-known bug in JavaScript. Although null represents the absence…