JavaScript adding decimal numbers issue

Question

So I am making a script that adds two numbers  decimal numbers  together  which I have encountered a problem   http   jsfiddle net DerekL esqnC   I made the script  it turns out pretty good   0 1   0 5    0 6 0 2   0 3    0 5   But soon I see   0 1   0 2    0 30000000000000004 0 01   0 06    0 06999999999999999   And it does not look right to me  I know it is a shortcoming of using float point with finite bits  but I can t find a way to fix that   Math ceil     No Math floor    No  slice        No   UPDATE  Is it possible to multiply the numbers by 1000 first  then add them then divide it by 1000

User · Answer

Testing this Javascript   var arr    1234563995 721  12345691212 718  1234568421 5891  12345677093 49284    var sum   0  for  var i   0  i  lt  arr length  i           sum    arr i      alert   fMath sum        Math round  sum   1e12     1e12    alert   fFixed sum        sum toFixed  5        Conclusion  Dont use Math round                         1e12    1e12  Instead  use                       toFixed 5     In IE 9  toFixed works very well

User · Answer

Use toFixed to convert it to a string with some decimal places shaved off  and then convert it back to a number     0 1   0 2  toFixed 12     0 3   It looks like IE s toFixed has some weird behavior  so if you need to support IE something like this might be better   Math round  0 1   0 2    1e12    1e12

User · Answer

This is common issue with floating points   Use toFixed in combination with parseFloat    Here is example in JavaScript   function roundNumber number  decimals        var newnumber   new Number number     toFixed parseInt decimals        return parseFloat newnumber       0 1   0 2                         gt  0 30000000000000004 roundNumber  0 1   0 2  12        gt  0 3

User · Answer

function add        var first parseFloat     first   val         var second parseFloat     second   val             result   val   first second  toFixed 2        DEMO

[javascript] JavaScript adding decimal numbers issue

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