How do I check that a number is float or integer

Question

How to find that a number is float or integer   1 25 -- gt  float   1 -- gt  integer   0 -- gt  integer   0 25 -- gt  float

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How about this one   isFloat num        return typeof num      number   amp  amp   Number isInteger num

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to check the number is Int or not and apply 2 decimal format  you can use the formula below in React-Native  isInt    n    gt            return n   1     0              show    x    gt            if x               if  this isInt x                    return   x                           else               return   x toFixed 2

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For those curious  using Benchmark js I tested the most up-voted answers  and the one posted today  on this post  here are my results   var n   -10 4375892034758293405790  var suite   new Benchmark Suite  suite        kennebec      add  0   function             return n   1    0                kennebec      add  1   function             return typeof n      number   amp  amp  n   1    0                kennebec      add  2   function             return typeof n      number   amp  amp  parseFloat n     parseInt n  10   amp  amp   isNaN n                  Axle      add  3   function             return n toString   indexOf          -1                 Dagg Nabbit      add  4   function             return n      n  amp  amp  n      n 0                  warfares      add  5   function             return parseInt n      n                 Marcio Simao      add  6   function             return   -  0-9     test n toString                    Tal Liron      add  7   function             if   undefined     n      null     n                 return false                    if  typeof n     number                 return true                    return  isNaN n - 0               Define logs and Run suite on  cycle   function event        console log String event target       on  complete   function         console log  Fastest is     this filter  fastest   pluck  name        run    async   true         0 x 12 832 357 ops sec   0 65   90 runs sampled  1 x 12 916 439 ops sec   0 62   95 runs sampled  2 x 2 776 583 ops sec   0 93   92 runs sampled  3 x 10 345 379 ops sec   0 49   97 runs sampled  4 x 53 766 106 ops sec   0 66   93 runs sampled  5 x 26 514 109 ops sec   2 72   93 runs sampled  6 x 10 146 270 ops sec   2 54   90 runs sampled  7 x 60 353 419 ops sec   0 35   97 runs sampled   Fastest is 7 Tal Liron

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Here are efficient functions that check if the value is a number or can be safely converted to a number   function isNumber value        if   undefined     value      null     value             return false            if  typeof value     number             return true            return  isNaN value - 0       And for integers  would return false if the value is a float    function isInteger value        if   undefined     value      null     value             return false            return value   1    0      The efficiency here is that parseInt  or parseNumber  are avoided when the value already is a number  Both parsing functions always convert to string first and then attempt to parse that string  which would be a waste if the value already is a number   Thank you to the other posts here for providing further ideas for optimization

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Any Float number with a zero decimal part  e g  1 0  12 00  0 0  are implicitly cast to Integer  so it is not possible to check if they are Float or not

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THIS IS FINAL CODE FOR CHECK BOTH INT AND FLOAT  function isInt n        if typeof n     number   amp  amp  Math Round n    1    0           return true       else          return false            OR   function isInt n          return typeof n     number   amp  amp  Math Round n    1    0

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check for a remainder when dividing by 1   function isInt n       return n   1     0      If you don t know that the argument is a number you need two tests   function isInt n       return Number n      n  amp  amp  n   1     0     function isFloat n       return Number n      n  amp  amp  n   1     0      Update 2019 5 years after this answer was written  a solution was standardized in ECMA Script 2015  That solution is covered in this answer

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Condtion for floating validation    if  lnk value     lnk value  amp  amp  lnk value     lnk value   0      Condtion for Integer validation    if  lnk value     lnk value  amp  amp  lnk value     lnk value   0      Hope this might be helpful

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Here s what I use for integers   Math ceil parseFloat val       val   Short  nice    Works all the time  This is what David Flanagan suggests if I m not mistaken

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Another method is       function isFloat float            return      test float toString             Might not be as efficient as the others but another method all the same

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function isInteger n       return   typeof n    number   amp  amp  n 1   0       function isFloat n       return   typeof n    number   amp  amp  n 1   0       function isNumber n       return  typeof n    number

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There is a method called Number isInteger   which is currently implemented in everything but IE  MDN also provides a polyfill for other browsers   Number isInteger   Number isInteger    function value      return typeof value      number   amp  amp       isFinite value   amp  amp       Math floor value      value       However  for most uses cases  you are better off using Number isSafeInteger   which also checks if the value is so high low that any decimal places would have been lost anyway  MDN has a polyfil for this as well   You also need the isInteger pollyfill above    if   Number MAX SAFE INTEGER        Number MAX SAFE INTEGER   9007199254740991     Math pow 2  53  - 1    Number isSafeInteger   Number isSafeInteger    function  value       return Number isInteger value   amp  amp  Math abs value   lt   Number MAX SAFE INTEGER

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I needed to check an input value if it s integer or float and to do that I ve come up with the following    x000D   x000D  function isInteger x    x000D    var integer   parseInt x  10   x000D    if   isNaN integer   amp  amp   isFloat x     x000D      return true  x000D      x000D    return false  x000D    x000D   x000D  function isFloat x    x000D    var f   parseFloat x   x000D    var floor   Math floor f   x000D    var fraction   f - floor  x000D    if  fraction  gt  0    x000D      return true  x000D      x000D    return false  x000D    x000D   x000D  var cases     x000D     1   x000D     1 00   x000D     1 01   x000D     0 05   x000D     ab1   x000D     ab1 1   x000D    1  x000D    1 00  x000D    1 01  x000D    0 05  x000D    1e 5  x000D        x000D    true  x000D    false  x000D    null  x000D    NaN  x000D    undefined  x000D     x000D   x000D  console log  isInteger      x000D  for  var i   0  i  lt  cases length  i      x000D    console log cases i   isInteger cases i     x000D    x000D   x000D  console log   nisFloat      x000D  for  var i   0  i  lt  cases length  i      x000D    console log cases i   isFloat cases i     x000D    x000D   x000D   x000D

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We can check by isInteger function  ie number will return true and float return false  console log Number isInteger 2    lt BR gt   Will return true   console log Number isInteger 2 5    Will return false

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For integers I use this  function integer or null value        if   undefined     value      null     value             return null            if value   1    0            return null            return value

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Why not something like this   var isInt   function n    return parseInt n      n

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try this  let n  return  n   value   1      0  amp  amp   isNaN n     when the return value is false means the input value is float number or float string  otherwise the input value is integer numbef or integer string   basically it needs to check the precision value for not equal to zero   another one is to check the correct string number also

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As others mentioned  you only have doubles in JS  So how do you define a number being an integer  Just check if the rounded number is equal to itself   function isInteger f        return typeof f     number   amp  amp  Math round f     f    function isFloat f    return typeof f     number   amp  amp   isInteger f

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var isInt   function  n    return n      n   0        Haven t had a case where this didn t do the job

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I find this the most elegant way   function isInteger n        return n      n 0       It cares also to return false in case of a non-numeric value

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With this you can check if a string or a number is  quot decimal quot   float properly   var IsDecimal   function num       return   num toString   split      length   lt   2  amp  amp  num toString   match       -   d     d     Ee     -   d            isNaN Number parseFloat num      false      and this other works for check if a string or a number is Integer  var IsInteger   function num       return   num toString   split      length     1  amp  amp  num toString   match     -   d          isNaN Number parseInt num      false       x000D   x000D  var IsDecimal   function num       return   num toString   split      length   lt   2  amp  amp  num toString   match       -   d     d     Ee     -   d            isNaN Number parseFloat num      false      var IsInteger   function num       return   num toString   split      length     1  amp  amp  num toString   match     -   d          isNaN Number parseInt num      false       console log  -------------- As string --------------    console log  Integers     console log  0       IsInteger  0     console log  34       IsInteger  34     console log   34       IsInteger   34     console log  3 4       IsInteger  3 4     console log  3e       IsInteger  3e     console log  e3       IsInteger  e3     console log  -34       IsInteger  -34     console log  --34       IsInteger  --34     console log  034       IsInteger  034     console log  0-34       IsInteger  0-34     console log  Floats decimals     console log  0       IsDecimal  0     console log  64       IsDecimal  64     console log   64       IsDecimal   64     console log  6 4       IsDecimal  6 4     console log  6e2       IsDecimal  6e2     console log  6e       IsDecimal  6e     console log  e6       IsDecimal  e6     console log  -64       IsDecimal  -64     console log  --64       IsDecimal  --64     console log  064       IsDecimal  064     console log  0-64       IsDecimal  0-64     console log   n-------------- As numbers --------------    console log  Integers     console log  0       IsInteger 0    console log  34       IsInteger 34    console log   34       IsInteger 0 34    console log  3 4       IsInteger 3 4    console log  -34       IsInteger -34    console log  034       IsInteger 034    console log  0-34       IsInteger 0-34    console log  Floats decimals     console log  0       IsDecimal 0    console log  64       IsDecimal 64    console log   64       IsDecimal 0 64    console log  6 4       IsDecimal 6 4    console log  6e2       IsDecimal 6e2    console log  -64       IsDecimal -64    console log  064       IsDecimal 064    console log  0-64       IsDecimal 0-64    x000D   x000D   x000D

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This is mine   function isInt quale        var valore         quale  val   toLowerCase        if  isNaN Number String valore        valore indexOf  e    gt  0                Not int       else              Is Int            And this   function isFloat quale       var valore         quale  val       valore   valore replace              if  isNaN String valore       valore indexOf  e    gt  0            Not Float      else          Float          Ad majora

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parseInt yourNumber     parseFloat yourNumber

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The functions below guard against empty strings undefines nulls  and max min value ranges  The Javascript engine should have built in these functions from day one      Enjoy   function IsInteger iVal        var iParsedVal    our internal converted int value       iParsedVal   parseInt iVal 10        if  isNaN iParsedVal     Infinity    iParsedVal    -Infinity    iParsedVal    sanity check - guard against empty strings and max min values         return false      else         return Number iVal       iParsedVal   0     the 2nd operand group  intValue   0   evaluates to true only if the intValue is an integer  so an int type will only return true    function IsFloat fVal        var fParsedVal    our internal converted float value       fParsedVal   parseFloat fVal        if  isNaN fParsedVal     Infinity    fParsedVal    -Infinity    fParsedVal    sanity check - guard against empty strings and max min values         return false      else         return    fVal   1     true only if there is a fractional value after the mod op  the    returns the opposite value of the op which reflects the function s return value

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For Float var decimal      -    0-9     0-9        if   price match decimal           alert  Please enter valid float          return false         For integer var number      d       if   price match number           alert  Please enter valid integer          return false

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It s simple as   if  n     parseInt n          Try this in console   x 1  x   parseInt x      true x  1   x   parseInt x      false x 1 1  x   parseInt x      false  obviously     BUT   x 1 0  x   parseInt x      true  because 1 0 is NOT a float    This confuses a lot of people   Whenever something is  0  it s not a float anymore   It s an integer   Or you can just call it  a numeric thing  for there is no strict distinction like back then in C   Good old times   So basically  all you can do is check for integer accepting the fact that 1 000 is an integer   Interesting side note  There was a comment about huge numbers   Huge numbers mean NO problem for this approach  whenever parseInt is unable to handle the number  for it s too big  it will return something else than the actual value so the test will return FALSE   This is a good thing because if you consider something a  number  you normally expect JS to be able to calculate with it - so yes  numbers are limited and parseInt will take this into consideration  to put it this way   Try this    lt script gt   var a   99999999999999999999  var b   999999999999999999999     just one more 9 will kill the show  var aIsInteger    a   parseInt a    a is ok   a fails   var bIsInteger    b   parseInt b    b is ok   b fails   alert aIsInteger      bIsInteger     lt  script gt    In my browser  IE8  this returns  a is ok  b fails  which is exactly because of the huge number in b   The limit may vary but I guess 20 digits  ought to be enough for anybody   to quote a classical

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It really doesn t have to be so complicated  The numeric value of an integer s parseFloat   and parseInt   equivalents will be the same  Thus you can do like so   function isInt value        return  parseFloat value     parseInt value    amp  amp   isNaN value       Then  if  isInt x      do work   This will also allow for string checks and thus is not strict  If want a strong type solution  aka  wont work with strings    function is int value   return  isNaN parseInt value   1

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Trying some of the answers here I ended up writing this solution  This works also with numbers inside a string   function isInt number        if          0 1  -  0 1  d 0      0 1  d        0 1    test number   return false      return   number - parseInt number       function isFloat number        if          0 1  -  0 1  d 0      0 1  d        0 1    test number   return false      return number - parseInt number    true   false       x000D   x000D      var tests     x000D           integer    1  x000D           float    1 1  x000D           integerInString     5   x000D           floatInString     5 5   x000D           negativeInt    -345  x000D           negativeFloat    -34 98  x000D           negativeIntString     -45   x000D           negativeFloatString     -23 09   x000D           notValidFalse    false  x000D           notValidTrue    true  x000D           notValidString     45lorem   x000D           notValidStringFloat     4 5lorem   x000D           notValidNan    NaN  x000D           notValidObj        x000D           notValidArr     1 2   x000D         x000D   x000D      function isInt number    x000D          if          0 1  -  0 1  d 0      0 1  d        0 1    test number   return false  x000D          return   number - parseInt number    x000D        x000D       x000D      function isFloat number    x000D          if          0 1  -  0 1  d 0      0 1  d        0 1    test number   return false  x000D          return number - parseInt number    true   false  x000D        x000D   x000D      function testFunctions obj    x000D          var keys   Object keys obj   x000D          var values   Object values obj   x000D   x000D          values forEach function element  index   x000D              console log  Is   keys index      element   var an integer    isInt element      x000D              console log  Is   keys index      element   var a float    isFloat element      x000D              x000D        x000D   x000D      testFunctions tests   x000D   x000D   x000D

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This solution worked for me    lt html gt   lt body gt     lt form method  post  action     gt       lt input type  text  id  number id   gt       lt input type  submit  value  send   gt     lt  form gt     lt p id  message  gt  lt  p gt     lt script gt      var flt document getElementById  number id   value      if isNaN flt   false  amp  amp  Number isInteger flt   false             document getElementById  message   innerHTML  the number id is a float             else            document getElementById  message   innerHTML  the number id is a Integer           lt  script gt   lt  body gt   lt  html gt

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function int a      return a - a     0  amp  amp  a toString 32  indexOf          -1    function float a      return a - a     0  amp  amp  a toString 32  indexOf          -1     You can add typeof a      number  if you want to exclude strings

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Some times Number objects don t allow you to use direct the mod operator      if you are facing that case you can use this solution   if object instanceof Number       if    Number  object  doubleValue     1    0             your object is an integer         else          your object is a double

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Based on all that I have seen here  I ve created my own set of functions to test for what I need   function NumberValidator     this isFloat   function  n        return typeof n     number   amp  amp  n      n  amp  amp  Math round n      n      this isInteger   function  n        return typeof n     number   amp  amp  n      n  amp  amp  Math round n      n      this isFloatOrInteger   function  n        return this isFloat n     this isInteger n       this isNonZeroFloatOrInteger   function  n        return this isFloatOrInteger n   amp  amp  n  gt  0      this isNonZeroInteger   function  n        return this isInteger n   amp  amp  n  gt  0         However  shime s solution is shorter and with less checks  so it might be a better one

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In java script all the numbers are internally 64 bit floating point  same as double in java  There are no diffrent types in javascript  all are represented by type number  Hence you wil l not be able make a instanceof check  However u can use the above solutions given to find out if it is a fractional number  designers of java script felt with a single type they can avoid numerous type cast errors

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You can use the Number isInteger   method to check if the number is an integer or a float by dividing them for example       function isNumberFloatOrInteger a  b        if Number isInteger a   b          return true                else  return false        Note  isInteger   is not compatible with internet explorer

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This maybe isn t as performant as the   answer  which prevents you from having to convert to a string first  but I haven t seen anyone post it yet  so here s another option that should work fine   function isInteger num        return num toString   indexOf          -1

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Here s my code   It checks to make sure it s not an empty string  which will otherwise pass  and then converts it to numeric format   Now  depending on whether you want  1 1  to be equal to 1 1  this may or may not be what you re looking for     var isFloat   function n        n   n length  gt  0   Number n    false      return  n     parseFloat n       var isInteger   function n        n   n length  gt  0   Number n    false      return  n     parseInt n        var isNumeric   function n       if isInteger n     isFloat n            return true          return false

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YourJS provides the following two functions which work for all numbers including returning false for -Infinity and Infinity   function isFloat x      return typeOf x   Number    amp  amp     x   1      function isInt x      return typeOf x   Number    amp  amp  x   1    0      Due to the fact that typeOf   is a YourJS internal function  if you wanted to use these definitions you can download the version for just these functions here   http   yourjs com snippets build 34

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You can use a simple regular expression   function isInt value         var er     -  0-9           return er test value       Or you can use the below functions too  according your needs  They are developed by the PHPJS Project   is int      Check if variable type is integer and if its content is integer  is float      Check if variable type is float and if its content is float  ctype digit      Check if variable type is string and if its content has only decimal digits  Update 1  Now it checks negative numbers too  thanks for  ChrisBartley comment

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try this one function amountcheck                 var dpamt     dpamt   val   5000          var ints dpamt toString            var isint ints split               if isint 1  gt 0                        alert  float value                return false                    else                          alert  int value

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24 1     false    24 2 1     true

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It really depends on what you want to achieve  If you want to  emulate  strongly typed languages then I suggest you not trying  As others mentioned all numbers have the same representation  the same type    Using something like Claudiu provided   isInteger  1 0   -  true  which looks fine for common sense  but in something like C you would get false

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I like this little function  which will return true for both positive and negative integers   function isInt val        return   string   number   indexOf typeof val    gt  -1  amp  amp  val         amp  amp   isNaN val   0        This works because 1 or  1  becomes  1 0   which isNaN   returns false on  which we then negate and return   but 1 0 or  1 0  becomes  1 0 0   while  string  becomes  string 0   neither of which are numbers  so isNaN   returns false  and  again  gets negated    If you only want positive integers  there s this variant   function isPositiveInt val        return   string   number   indexOf typeof val    gt  -1  amp  amp  val         amp  amp   isNaN  0  val       or  for negative integers   function isNegativeInt val        return    string   number   indexOf typeof val    gt  -1   amp  amp  val         amp  amp  isNaN  0  val       isPositiveInt   works by moving the concatenated numeric string ahead of the value to be tested  For example  isPositiveInt 1  results in isNaN   evaluating  01   which evaluates false  Meanwhile  isPositiveInt -1  results in isNaN   evaluating  0-1   which evaluates true  We negate the return value and that gives us what we want  isNegativeInt   works similarly  but without negating the return value of isNaN     Edit   My original implementation would also return true on arrays and empty strings  This implementation doe not have that defect  It also has the benefit of returning early if val is not a string or number  or if it s an empty string  making it faster in these cases  You can further modify it by replacing the first two clauses with  typeof val      number    if you only want to match literal numbers  and not strings   Edit   I can t post comments yet  so I m adding this to my answer  The benchmark posted by  Asok is very informative  however  the fastest function does not fit the requirements  as it also returns TRUE for floats  arrays  booleans  and empty strings   I created the following test suite to test each of the functions  adding my answer to the list  as well  function 8  which parses strings  and function 9  which does not    funcs         function n            return n   1    0             function n            return typeof n      number   amp  amp  n   1    0             function n            return typeof n      number   amp  amp  parseFloat n     parseInt n  10   amp  amp   isNaN n              function n            return n toString   indexOf          -1             function n            return n      n  amp  amp  n      n 0              function n            return parseInt n      n             function n            return   -  0-9     test n toString                function n            if   undefined     n      null     n                 return false                    if  typeof n     number                 return true                    return  isNaN n - 0              function n            return   string   number   indexOf typeof n    gt  -1  amp  amp  n         amp  amp   isNaN n   0             vals          1 true        -1 true        1 1 false        -1 1 false           false           false        true false        false false        null false           false         a  false         1  null         -1  null         1 1  null         -1 1  null      for  var i in funcs        var pass   true      console log  Testing function   i       for  var ii in vals            var n   vals ii  0           var ns          if  n     null                ns   n               else               switch  typeof n                     case  string                       ns         n                            break                  case  object                       ns   Object prototype toString call n                       break                  default                      ns   n                            ns       typeof n       ns                     var x   vals ii  1           var xs          if  x     null                xs     ANY              else               switch  typeof x                     case  string                       xs         n                            break                  case  object                       xs   Object prototype toString call x                       break                  default                      xs   x                            xs       typeof x       xs                     var rms          try               var r   funcs i  n               var rs              if  r     null                    rs   r                   else                   switch  typeof r                         case  string                           rs         r                                break                      case  object                           rs   Object prototype toString call r                           break                      default                          rs   r                                    rs       typeof r       rs                             var m              var ms              if  x     null                    m   true                  ms    N A                 else if  typeof x      object                     m    xs     rs                   ms   m                else                   m    x     r                   ms   m                            if   m                    pass   false                            rms    Result    rs    Match    ms            catch  e                rms    Test skipped  function threw exception                      console log      Value    ns    Expect    xs      rms             console log pass    PASS      FAIL         I also reran the benchmark with function  8 added to the list  I won t post the result  as they re a bit embarrassing  e g  that function is NOT fast      The  abridged -- I removed successful tests  since the output is quite long  results are as follows   Testing function 0 Value   object   object Array   Expect   boolean  false  Result   boolean  true  Match  false Value   boolean  true  Expect   boolean  false  Result   boolean  true  Match  false Value   boolean  false  Expect   boolean  false  Result   boolean  true  Match  false Value  null  Expect   boolean  false  Result   boolean  true  Match  false Value   string      Expect   boolean  false  Result   boolean  true  Match  false Value   string   1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1   Expect   ANY   Result   boolean  true  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A FAIL   Testing function 1 Value   string   1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1   Expect   ANY   Result   boolean  false  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 2 Value   string   1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1   Expect   ANY   Result   boolean  false  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 3 Value   object  true  Expect   boolean  false  Result   boolean  true  Match  false Value   object  false  Expect   boolean  false  Result   boolean  true  Match  false Value   boolean   object Array   Expect   boolean  false  Result   boolean  true  Match  false Value   boolean   object Object   Expect   boolean  false  Result   boolean  true  Match  false Value  null  Expect   boolean  false  Test skipped  function threw exception  Value   string      Expect   boolean  false  Result   boolean  true  Match  false Value   string   a   Expect   boolean  false  Result   boolean  true  Match  false Value   string   1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1   Expect   ANY   Result   boolean  true  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A FAIL   Testing function 4 Value   string   1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1   Expect   ANY   Result   boolean  false  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 5 Value   string   1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1   Expect   ANY   Result   boolean  false  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 6 Value  null  Expect   boolean  false  Test skipped  function threw exception  Value   string   1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1   Expect   ANY   Result   boolean  true  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 7 Value   number  1 1  Expect   boolean  false  Result   boolean  true  Match  false Value   number  -1 1  Expect   boolean  false  Result   boolean  true  Match  false Value   object  true  Expect   boolean  false  Result   boolean  true  Match  false Value   boolean   object Array   Expect   boolean  false  Result   boolean  true  Match  false Value   boolean   object Object   Expect   boolean  false  Result   boolean  true  Match  false Value   string      Expect   boolean  false  Result   boolean  true  Match  false Value   string   1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1   Expect   ANY   Result   boolean  true  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  true  Match  N A FAIL   Testing function 8 Value   string   1   Expect   ANY   Result   boolean  true  Match  N A Value   string   -1   Expect   ANY   Result   boolean  true  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS   Testing function 9 Value   string   1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1   Expect   ANY   Result   boolean  false  Match  N A Value   string   1 1   Expect   ANY   Result   boolean  false  Match  N A Value   string   -1 1   Expect   ANY   Result   boolean  false  Match  N A PASS    I ve left in failures so you can see where each function is failing  and the  string      tests so you can see how each function handles integer and float values in strings  as some may want these parsed as numbers and some may not   Out of the 10 functions tested  the ones that actually fit OP s requirements are  1 3 5 6 8 9

User · Answer

function isInt n         return n        amp  amp   isNaN n   amp  amp  Math round n     n    function isFloat n       return n        amp  amp   isNaN n   amp  amp  Math round n     n      works for all cases

User · Answer

function isInteger x    return typeof x      number   amp  amp  isFinite x   amp  amp  Math floor x      x    function isFloat x    return    x   1         give it a spin  isInteger 1 0             true isFloat 1 0               false isFloat 1 2               true isInteger 1 2             false isFloat 1                 false isInteger 1               true     isFloat 2e 2              false isInteger 2e 2            true isFloat  1                false isInteger  1              false isFloat NaN               false isInteger NaN             false isFloat null              false isInteger null            false isFloat undefined         false isInteger undefined       false

User · Answer

There is Number isInteger number  to check this  Doesn t work in Internet Explorer but that browser isn t used anymore  If you need string like  90  to be an integer  which wasnt the question  try Number isInteger Number number    The  official  isInteger considers 9 0 as an integer  see https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Number  It looks like most answers are correct for older browsers but modern browsers have moved on and actually support float integer check

User · Answer

Try these functions to test whether a value is a number primitive value that has no fractional part and is within the size limits of what can be represented as an exact integer   function isFloat n        return n      n  amp  amp  n      n 0      function isInteger n        return n      n  amp  amp  n      n 0

[javascript] How do I check that a number is float or integer?

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