How to deal with floating point number precision in JavaScript?

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From the Floating-Point Guide:

What can I do to avoid this problem?

That depends on what kind of
calculations you’re doing.

  • If you really need your results to add up exactly, especially when you
    work with money: use a special decimal
    datatype.
  • If you just don’t want to see all those extra decimal places: simply
    format your result rounded to a fixed
    number of decimal places when
    displaying it.
  • If you have no decimal datatype available, an alternative is to work
    with integers, e.g. do money
    calculations entirely in cents. But
    this is more work and has some
    drawbacks.

Note that the first point only applies if you really need specific precise decimal behaviour. Most people don’t need that, they’re just irritated that their programs don’t work correctly with numbers like 1/10 without realizing that they wouldn’t even blink at the same error if it occurred with 1/3.

If the first point really applies to you, use BigDecimal for JavaScript, which is not elegant at all, but actually solves the problem rather than providing an imperfect workaround.

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