Incorrect result of Number.MIN_VALUE - 1 in JavaScript

Question

console.log(Number.MIN_VALUE);  // 5e-324
console.log(Number.MIN_VALUE - 1); // -1

Value of Number.MIN_VALUE is 5e-324, but if I subtract 1 from it, -1 is returned.

It looks like some garbage value but I'm wondering why JavaScript interpreter cannot represent it. Otherwise, Number.MAX_VALUE + 1 is same with Number.MAX_VALUE(1.7976931348623157e+308).

Is there something different between calculating Numbers.MAX_VALUE and Numbers.MIN_VALUE?

score 1 · Accepted Answer · answered Feb 28 '19 at 11:10

Number.MIN_VALUE - 1 is equal to -0.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999

I think any reasonable person would consider that to be -1, even before accounting for things like floating point inaccuracy :)

To be clear, Number.MIN_VALUE is the smallest value greater than zero that can be represented. It is not "negative Number.MAX_VALUE" as you appear to expect.

@AndrewMorton Honestly I have no idea - probably, but the exact value is going to have 15 significant digits after all the 9s... Oops. — Niet the Dark Absol, Feb 28 '19 at 11:13

Incorrect result of Number.MIN_VALUE - 1 in JavaScript

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