this post was submitted on 25 Sep 2024
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Programming

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Why is 0.1 + 0.2 returns 0.30000000000000004 in JavaScript? (medium.com)
submitted 3 days ago by gyanendraknojiya@programming.dev to c/programming@programming.dev
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Have you performed simple arithmetic operations like 0.1 + 0.2? You might have gotten something strange: 0.1 + 0.2 = 0.30000000000000004.

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[–] aubeynarf@lemmynsfw.com 2 points 3 days ago* (last edited 3 days ago) (5 children)

JavaScript is truly a bizarre language - we don’t need to go as far as arbitrary-precision decimal, it does not even feature integers.

I have to wonder why it ever makes the cut as a backend language.

[–] luciole@beehaw.org 1 points 3 days ago (1 children)

The JavaScript Number type is implemented as an IEEE 754 double and as such any integer between -2^53^ and 2^53^ are represented without loss of precision. I can’t say I’ve ever missed explicitly declaring a value as an integer in JS. It’s dynamically typed anyways. There’s the languages people complain about and the ones nobody uses.

[–] aubeynarf@lemmynsfw.com 1 points 3 days ago (1 children)

And then JSON doesn’t restrict numbers to any range or precision; and at least when I deal with JSON values, I feel the need to represent them as a BigDecimal or similar arbitrary precision type to ensure I am not losing information.

[–] luciole@beehaw.org 1 points 3 days ago* (last edited 3 days ago) (1 children)

I hope you work in a field where worrying about your integers hitting larger values than 9 quadrillion is justified.

[–] aubeynarf@lemmynsfw.com 3 points 3 days ago* (last edited 3 days ago)

Could be a crypto key, or a randomly distributed 64-bit database row ID, or a memory offset in a stack dump of a 64 bit program

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