Check if string contains only digits

Question

I want to check if a string contains only digits  I used this   var isANumber   isNaN theValue      false   if  isANumber              But realized that it also allows   and -  Basically  I wanna make sure an input contains ONLY digits and no other characters  Since  100 and -5 are both numbers  isNaN   is not the right way to go  Perhaps a regexp is what I need  Any tips

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string match    0-9         null

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This is what you want  function isANumber str     return    D  test str

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x000D   x000D  var str  1232323a 1   var reg    0-9       0-9       console log reg test str   x000D   x000D   x000D

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function isNumeric x        return parseFloat x  toString       x toString        Though this will return false on strings with leading or trailing zeroes

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Here is a solution without using regular expressions   function onlyDigits s      for  let i   s length - 1  i  gt   0  i--        const d   s charCodeAt i       if  d  lt  48    d  gt  57  return false       return true     where 48 and 57 are the char codes for  0  and  9   respectively

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String prototype isNumber   function   return    d    test this    console log  123123  isNumber        outputs true console log   12  isNumber        outputs false

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If you use jQuery    isNumeric  1234       true   isNumeric  1ab4       false

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if you want to include float values also you can use the following code   theValue     balanceinput   val    var isnum1      d     d    test theValue   var isnum2       d     d    test theValue split     reverse   join       alert isnum1     isnum2     this will test for only digits and digits separated with     the first test will cover values such as 0 1 and 0 but also  1    it will not allow 0   so the solution that I propose is to reverse theValue so  1 will be 1  then the same regular expression will not allow it    example      theValue 3 4    isnum1 true   isnum2 true  theValue  4    isnum1 true   isnum2 false  theValue 3     isnum1 flase   isnum2 true

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Here s a Solution without using regex const  isdigit  value   gt       const val Number value  true false     console log val       return val    isdigit  quot 10 quot    true isdigit  quot any String quot    false

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Here s another interesting  readable way to check if a string contains only digits   This method works by splitting the string into an array using the spread operator  and then uses the every   method to test whether all elements  characters  in the array are included in the string of digits  0123456789     x000D   x000D  const digits only   string   gt      string  every c   gt   0123456789  includes c    x000D   x000D  console log digits only  123        true x000D  console log digits only   123        false x000D  console log digits only  -123        false x000D  console log digits only  123         false x000D  console log digits only   123        false x000D  console log digits only  123 0        false x000D  console log digits only  0 123        false x000D  console log digits only  Hello  world         false x000D   x000D   x000D

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how about  let isnum      d    test val

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Well  you can use the following regex     d

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If you want to even support for float values  Dot separated values  then you can use this expression     var isNumber      d    d    test value

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it checks valid number integers or float or double not a string regex that i used simple regex  1    0-9       0-9     advance regex  2   -   d      e-  d          eg only numbers  x000D   x000D  var str  1232323   var reg    0-9       0-9       console log reg test str   x000D   x000D   x000D   it allows eg 123434 eg  1232323 eg 12 3434434 it does not allow eg 1122212 efsffasf eg 2323fdf34434 eg 0 3232rf3333 advance regex                                                                      int or float or exponent all types of number in string  -   d      e-  d      eg 13123123 eg 12344 3232 eg 2323323e4 eg 0 232332

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in case you need integer and float at same validation    d    d     d    test val

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c  123  match   D      null  true c  a12  match   D      null  false   If a string contains only digits it will return null

[javascript] Check if string contains only digits

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