How can I find the length of a number

Question

I m looking to get the length of a number in JavaScript or jQuery   I ve tried value length without any success  do I need to convert this to a string first

User · Answer

First convert it to a string   var mynumber   123  alert     mynumber  length     Adding an empty string to it will implicitly cause mynumber to turn into a string

User · Answer

I ve been using this functionality in node js  this is my fastest implementation so far   var nLength   function n         return  Math log Math abs n  1    0 43429448190325176   0    1        It should handle positive and negative integers  also in exponential form  and should return the length of integer part in floats   The following reference should provide some insight into the method  Weisstein  Eric W   Number Length   From MathWorld--A Wolfram Web Resource   I believe that some bitwise operation can replace the Math abs  but jsperf shows that Math abs works just fine in the majority of js engines   Update  As noted in the comments  this solution has some issues     Update2  workaround    I believe that at some point precision issues kick in and the Math log      0 434    just behaves unexpectedly  However  if Internet Explorer or Mobile devices are not your cup of tea  you can replace this operation with the Math log10 function  In Node js I wrote a quick basic test with the function nLength    n    gt  1   Math log10 Math abs n    1    0  and with Math log10 it worked as expected  Please note that Math log10 is not universally supported

User · Answer

Yes you need to convert to string in order to find the length For example  var x 100    type of x is number var x 100       now the type of x is string document write x length    which would output 3

User · Answer

You should go for the simplest one  stringLength   readability always beats speed  But if you care about speed here are some below   Three different methods all with varying speed      34ms let weissteinLength   function n         return  Math log Math abs n  1    0 43429448190325176   0    1        350ms let stringLength   function n        return n toString   length        58ms let mathLength   function n        return Math ceil Math log n   1    Math LN10         Simple tests below if you care about performance   let iterations   1000000  let maxSize   10000      ------ Weisstein length   console log  Starting weissteinLength length     let startTime   Date now     for  let index   0  index  lt  iterations  index          weissteinLength Math random     maxSize      console log  Ended weissteinLength length  Took        Date now   - startTime      ms         ------- String length slowest   console log  Starting string length     startTime   Date now     for  let index   0  index  lt  iterations  index          stringLength Math random     maxSize      console log  Ended string length  Took        Date now   - startTime      ms         ------- Math length   console log  Starting math length     startTime   Date now     for  let index   0  index  lt  iterations  index          mathLength Math random     maxSize

User · Answer

Try this       element   text   length    Example of it in use

User · Answer

You have to make the number to string in order to take length  var num   123   alert  num       length     or   alert num toString   length

User · Answer

Well without converting the integer to a string you could make a funky loop   var number   20000  var length   0  for i   number  i  gt  1    i          length       i   Math floor i 10      alert length      Demo  http   jsfiddle net maniator G8tQE

User · Answer

A way for integers without banal converting to string  var num   9999999999     your number var length   1  while  num  gt   10       num    10     length      alert length

User · Answer

There are three way to do it   var num   123  alert num toString   length     better performance one  best performance in ie11   var num   123  alert  num       length     Math  best performance in Chrome  firefox but slowest in ie11   var num   123 alert Math floor  Math log num    Math LN10     1    there is a jspref here http   jsperf com fastest-way-to-get-the-first-in-a-number 2

User · Answer

Ok  so many answers  but this is a pure math one  just for the fun or for remembering that Math is Important   var len   Math ceil Math log num   1    Math LN10     This actually gives the  length  of the number even if it s in exponential form  num is supposed to be a non negative integer here  if it s negative  take its absolute value and adjust the sign afterwards   Update for ES2015  Now that Math log10 is a thing  you can simply write  const len   Math ceil Math log10 num   1

User · Answer

var x   1234567   x toString   length    This process will also work forFloat Number and for Exponential number also

User · Answer

I got asked a similar question in a test      Find a number s length without converting to string   const numbers    1  10  100  12  123  -1  -10  -100  -12  -123  0  -0   const numberLength   number   gt       let length   0   let n   Math abs number     do       n     10     length       while  n  gt   1     return length    console log numbers map numberLength        1  2  3  2  3  1  2  3  2  3  1  1     Negative numbers were added to complicate it a little more  hence the Math abs

User · Answer

I would like to correct the  Neal answer which was pretty good for integers  but the number 1 would return a length of 0 in the previous case   function Longueur numberlen        var length   0  i    define  i  with  var  as not to clutter the global scope     numberlen   parseInt numberlen       for i   numberlen  i  gt   1  i                  length          i   Math floor i 10             return length

User · Answer

Could also use a template string   const num   123456    num   length    6

[javascript] How can I find the length of a number?

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