puzzle 12 · javascript

What does this log?

console.log(0.1 + 0.2 === 0.3);
true
false
undefined
TypeError

why

IEEE-754 doubles can't represent 0.1 or 0.2 exactly, so the sum is 0.30000000000000004. Compare with a tolerance: Math.abs(a - b) < Number.EPSILON.

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