How do I convert a float number to a whole number in JavaScript

Question

I d like to convert a float to a whole number in JavaScript  Actually  I d like to know how to do BOTH of the standard conversions  by truncating and by rounding  And efficiently  not via converting to a string and parsing

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If look into native Math object in JavaScript  you get the whole bunch of functions to work on numbers and values  etc     Basically what you want to do is quite simple and native in JavaScript     Imagine you have the number below   const myValue   56 4534931    and now if you want to round it down to the nearest number  just simply do   const rounded   Math floor myValue     and you get   56   If you want to round it up to the nearest number  just do   const roundedUp   Math ceil myValue     and you get   57   Also Math round just round it to higher or lower number depends on which one is closer to the flot number   Also you can use of    behind the float number  that will convert a float to a whole number   You can use it like   myValue

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var intvalue   Math floor  floatvalue    var intvalue   Math ceil  floatvalue     var intvalue   Math round  floatvalue         Math trunc  was added in ECMAScript 6 var intvalue   Math trunc  floatvalue     Math object reference  Examples Positive    value x            x 5          5 lt x lt 5 5      5 5 lt  x lt 6    Math floor value      5            5            5 Math ceil value       5            6            6 Math round value      5            5            6 Math trunc value      5            5            5 parseInt value        5            5            5   value               5            5            5 value   0             5            5            5 value  gt  gt  0            5            5            5 value  gt  gt  gt  0           5            5            5 value - value   1     5            5            5  Negative    value x           x -5         -5 gt x gt  -5 5   -5 5 gt x gt -6  Math floor value     -5           -6           -6 Math ceil value      -5           -5           -5 Math round value     -5           -5           -6 Math trunc value     -5           -5           -5 parseInt value       -5           -5           -5 value   0            -5           -5           -5   value              -5           -5           -5 value  gt  gt  0           -5           -5           -5 value  gt  gt  gt  0          4294967291   4294967291   4294967291 value - value   1    -5           -5           -5  Positive - Larger numbers    x   Number MAX SAFE INTEGER 10     900719925474099 1     value x            x 900719925474099    x 900719925474099 4  x 900719925474099 5             Math floor value      900719925474099      900719925474099      900719925474099 Math ceil value       900719925474099      900719925474100      900719925474100 Math round value      900719925474099      900719925474099      900719925474100 Math trunc value      900719925474099      900719925474099      900719925474099 parseInt value        900719925474099      900719925474099      900719925474099 value   0             858993459            858993459            858993459   value               858993459            858993459            858993459 value  gt  gt  0            858993459            858993459            858993459 value  gt  gt  gt  0           858993459            858993459            858993459 value - value   1     900719925474099      900719925474099      900719925474099  Negative - Larger numbers    x   Number MAX SAFE INTEGER 10   -1    -900719925474099 1     value   x         x -900719925474099   x -900719925474099 5 x -900719925474099 6  Math floor value     -900719925474099     -900719925474100     -900719925474100 Math ceil value      -900719925474099     -900719925474099     -900719925474099 Math round value     -900719925474099     -900719925474099     -900719925474100 Math trunc value     -900719925474099     -900719925474099     -900719925474099 parseInt value       -900719925474099     -900719925474099     -900719925474099 value   0            -858993459           -858993459           -858993459   value              -858993459           -858993459           -858993459 value  gt  gt  0           -858993459           -858993459           -858993459 value  gt  gt  gt  0           3435973837           3435973837           3435973837 value - value   1    -900719925474099     -900719925474099     -900719925474099

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Bit shift by 0 which is equivalent to division by 1      gt  gt  or  gt  gt  gt  2 0  gt  gt  0     2 2 0  gt  gt  gt  0     2

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A double bitwise not operator can be used to truncate floats   The other operations you mentioned are available through Math floor  Math ceil  and Math round    gt    2 5 2  gt     -1 4  -1   More details courtesy of James Padolsey

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Bitwise OR operator  A bitwise or operator can be used to truncate floating point figures and it works for positives as well as negatives   function float2int  value        return value   0      Results  float2int 3 1     3 float2int -3 1     -3 float2int 3 9     3 float2int -3 9     -3   Performance comparison   I ve created a JSPerf test that compares performance between    Math floor val  val   0 bitwise OR   val bitwise NOT parseInt val    that only works with positive numbers  In this case you re safe to use bitwise operations well as Math floor function   But if you need your code to work with positives as well as negatives  then a bitwise operation is the fastest  OR being the preferred one   This other JSPerf test compares the same where it s pretty obvious that because of the additional sign checking Math is now the slowest of the four   Note  As stated in comments  BITWISE operators operate on signed 32bit integers  therefore large numbers will be converted  example   1234567890    0   gt  1234567890 12345678901   0   gt  -539222987

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Note  You cannot use Math floor   as a replacement for truncate  because Math floor -3 1    -4 and not -3     A correct replacement for truncate would be   function truncate value        if  value  lt  0            return Math ceil value              return Math floor value

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You can use the parseInt method for no rounding   Be careful with user input due to the 0x  hex  and 0  octal  prefix options   var intValue   parseInt floatValue  10

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x000D   x000D    Convert a float to integer x000D   x000D  Math floor 5 95  x000D    5 x000D   x000D  Math ceil 5 95  x000D    6 x000D   x000D  Math round 5 4  x000D    5 x000D   x000D  Math round 5 5  x000D    6 x000D   x000D  Math trunc 5 5  x000D    5 x000D   x000D    Quick Ways x000D  console log 5 95  0  x000D  console log   5 95   x000D  console log 5 95  gt  gt  0  x000D    5 x000D   x000D   x000D

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There are many suggestions here  The bitwise OR seems to be the simplest by far  Here is another short solution which works with negative numbers as well using the modulo operator  It is probably easier to understand than the bitwise OR   intval   floatval - floatval 1    This method also works with high value numbers where neither   0  nor      nor    0  work correctly    gt  n 4294967295   gt  n 0 -1  gt    n -1  gt  n gt  gt 0 -1  gt  n-n 1 4294967295

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One more possible way     use XOR operation   x000D   x000D  console log 12 3   0      12 console log  12 3    0      12 console log 1 2   1 3   0      2 console log 1 2   1 3   2   0      3 console log -1 2   0      -1 console log -1 2   1   0      0 console log -1 2 - 1 3   0      -2 x000D   x000D   x000D   Priority of bitwise operations is less then priority of math operations  it s useful  Try on https   jsfiddle net au51uj3r

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Performance Today 2020 11 28 I perform tests on MacOs HighSierra 10 13 6 on Chrome v85  Safari v13 1 2 and Firefox v80 for chosen solutions  Results  for all browsers all solutions  except B and K  gives very similar speed results solutions B and K are slow   Details I perform test case which you can run HERE Below snippet presents differences between solutions A B C D E F G H I J K L  x000D   x000D  function A float        return Math trunc  float       function B float        return parseInt float      function C float        return float   0     function D float        return   float     function E float        return float  gt  gt  0     function F float        return float - float 1     function G float        return float   0     function H float        return Math floor  float       function I float        return Math ceil  float       function J float        return Math round  float       function K float        return float toFixed 0      function L float        return float  gt  gt  gt  0             ---------    TEST    ---------   A B C D E F G H I J K L     forEach f  gt  console log    f name    f 1 5     f -1 5     f 2 499     f -2 499      x000D  This snippet only presents functions used in performance tests - it not perform tests itself  x000D   x000D   x000D   And here are example results for chrome

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If you are using angularjs then simple solution as follows In HTML Template Binding     val   number 0     it will convert val into integer  go through with this link docs angularjs org api ng filter number

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In your case  when you want a string in the end  in order to insert commas   you can also just  use the Number toFixed   function  however  this will perform rounding

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I just want to point out that monetarily you want to round  and not trunc  Being off by a penny is much less likely  since 4 999452   100 rounded will give you 5  a more representative answer   And on top of that  don t forget about banker s rounding  which is a way to counter the slightly positive bias that straight rounding gives -- your financial application may require it   Gaussian banker  39 s rounding in JavaScript

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To truncate   x000D   x000D     Math trunc   is part of the ES6 spec console log Math trunc  1 5         returns 1 console log Math trunc  -1 5        returns -1    Math floor  -1 5   would return -2  which is probably not what you wanted x000D   x000D   x000D   To round   x000D   x000D  console log Math round  1 5         2 console log Math round  1 49        1 console log Math round  -1 6        -2 console log Math round  -1 3        -1 x000D   x000D   x000D

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For truncate   var intvalue   Math floor value     For round   var intvalue   Math round value

[javascript] How do I convert a float number to a whole number in JavaScript?

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