How can I round a number in JavaScript toFixed returns a string

Question

Am I missing something here   var someNumber   123 456  someNumber   someNumber toFixed 2   alert typeof someNumber      alerts string   Why does  toFixed   return a string   I want to round the number to 2 decimal digits

User · Answer

Because its primary use is displaying numbers  If you want to round numbers  use Math round   with apropriate factors

User · Answer

Here s a slightly more functional version of the answer m93a provided   const toFixedNumber    toFixTo   2  base   10    gt  num   gt      const pow   Math pow base  toFixTo    return   Math round num   pow    pow     const oneNumber   10 12323223  const result1   toFixedNumber 2  oneNumber     10 12 const result2   toFixedNumber 3  oneNumber     10 123     or using pipeline-operator const result3   oneNumber   gt  toFixedNumber 2     10 12

User · Answer

Of course it returns a string   If you wanted to round the numeric variable you d use Math round   instead   The point of toFixed is to format the number with a fixed number of decimal places for display to the user

User · Answer

Why not   the result by 1 i e someNumber toFixed 2    1

User · Answer

For others like me that happen upon this very old question  a modern solution  const roundValue    num  decimals   2    gt        let scaling   10    decimals      return Math round  num   Number EPSILON    scaling    scaling     ref  https   stackoverflow com a 11832950

User · Answer

You should use it like below  var someNumber  number   0 000000  someNumber   Number someNumber toFixed 2

User · Answer

Why not use parseFloat   var someNumber   123 456  someNumber   parseFloat someNumber toFixed 2    alert typeof someNumber      alerts number

User · Answer

What would you expect it to return when it s supposed to format a number   If you have a number you can t pretty much do anything with it because e g 2    2 0    2 00 etc  so it has to be a string

User · Answer

I solved it with converting it back to number using JavaScript s Number   function  var x   2 2873424  x   Number x toFixed 2

User · Answer

It returns a string because 0 1  and powers thereof  which are used to display decimal fractions   are not representable  at least not with full accuracy  in binary floating-point systems   For example  0 1 is really 0 1000000000000000055511151231257827021181583404541015625  and 0 01 is really 0 01000000000000000020816681711721685132943093776702880859375   Thanks to BigDecimal for proving my point   -P   Therefore  absent a decimal floating point or rational number type   outputting it as a string is the only way to get it trimmed to exactly the precision required for display

User · Answer

May be too late to answer but you can multiple the output with 1 to convert to number again  here is an example   x000D   x000D  const x1   1211 1212121  const x2   x1 toFixed 2  1  console log typeof x2    x000D   x000D   x000D

User · Answer

To supply an example of why it has to be a string   If you format 1 toFixed 2  you would get  1 00    This is not the same as 1  as 1 does not have 2 decimals     I know JavaScript isn t exactly a performance language  but chances are you d get better performance for a rounding if you use something like  roundedValue   Math round value   100    0 01

User · Answer

You can simply use a     to convert the result to a number   var x   22 032423  x    x toFixed 2      x   22 03

User · Answer

Number prototype toFixed is a function designed to format a number before printing it out  It s  from the family of toString  toExponential and toPrecision   To round a number  you would do this   someNumber   42 008  someNumber   Math round  someNumber   1e2     1e2  someNumber     42 01      if you need 3 digits  replace 1e2 with 1e3 etc     or just copypaste this function to your code   function toFixedNumber num  digits  base     var pow   Math pow base  10  digits     return Math round num pow    pow         Or if you want a    native-like    function  you can extend the prototype   Number prototype toFixedNumber   function digits  base     var pow   Math pow base  10  digits     return Math round this pow    pow      someNumber   42 008  someNumber   someNumber toFixedNumber 2   someNumber     42 01      or even hexadecimal  someNumber   0xAF309 256    which is af3 09 someNumber   someNumber toFixedNumber 1  16   someNumber toString 16       af3 1     However  bear in mind that polluting the prototype is considered bad when you re writing a module  as modules shouldn t have any side effects  So  for a module  use the first function

User · Answer

I ve solved this problem by changing this   someNumber   someNumber toFixed 2       to this   someNumber    someNumber toFixed 2     However this will convert the number to a string and parse it again  which will have a significant impact on performance  If you care about performance or type safety  check the the other answers as well

[javascript] How can I round a number in JavaScript? .toFixed() returns a string?

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