Dealing with float precision in Javascript

Question

I have a large amount of numeric values y in javascript   I want to group them by rounding them down to the nearest multiple of x and convert the result to a string    How do I get around the annoying floating point precision     For example   0 2   0 4   0 6000000000000001   Two things I have tried    gt  gt  gt  y   1 23456789   gt  gt  gt  x   0 2   gt  gt  gt  parseInt Math round Math floor y x      x   1 2000000000000002   and    gt  gt  gt  y   1 23456789   gt  gt  gt  x   0 2   gt  gt  gt  y -  y   x  1 2000000000000002

User · Answer

Tackling this task  I d first find the number of decimal places in x  then round y accordingly  I d use   y toFixed x toString   split      1  length     It should convert x to a string  split it over the decimal point  find the length of the right part  and then y toFixed length  should round y based on that length

User · Answer

You could do something like this    gt    Math floor y x  x  toFixed 15   1 2

User · Answer

gt  var x   0 1  gt  var y   0 2  gt  var cf   10  gt  x   y 0 020000000000000004  gt   x   cf     y   cf     cf   cf  0 02   Quick solution   var  cf    function       function  shift x        var parts   x toString   split           return  parts length  lt  2    1   Math pow 10  parts 1  length         return function          return Array prototype reduce call arguments  function  prev  next    return prev     undefined    next     undefined   undefined   Math max prev   shift  next       -Infinity               Math a   function        var f    cf apply null  arguments   if f     undefined  return undefined    function cb x  y  i  o    return x   f   y      return Array prototype reduce call arguments  cb  0    f      Math s   function  l r    var f    cf l r   return  l   f - r   f    f      Math m   function        var f    cf apply null  arguments     function cb x  y  i  o    return  x f     y f     f   f       return Array prototype reduce call arguments  cb  1       Math d   function  l r    var f    cf l r   return  l   f     r   f        gt  Math m 0 1  0 2  0 02   You can check the full explanation here

User · Answer

Check out this link   It helped me a lot   http   www w3schools com jsref jsref toprecision asp  The toPrecision no of digits required  function returns a string so don t forget to use the parseFloat   function to convert to decimal point of required precision

User · Answer

From this post  How to deal with floating point number precision in JavaScript   You have a few options    Use a special datatype for decimals  like decimal js Format your result to some fixed number of significant digits  like this   Math floor y x    x  toFixed 2  Convert all your numbers to integers

[javascript] Dealing with float precision in Javascript

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