Regex to check whether a string contains only numbers

Question

hash   window location hash substr 1   var reg   new RegExp    0-9      console log reg test hash      I get false on both  123  and  123f   I would like to check if the hash only contains numbers  Did I miss something

User · Answer

You need the   so it says  zero or more of the previous character  and this should do it   var reg   new RegExp     d

User · Answer

If the numbers aren t supposed to be absurdly huge  maybe use   new RegExp                                         No leading content        -                                Optional sign           0-9  0 30                     Optionally 0-30 decimal digits of mantissa        0-9  1 30                        1-30 decimal digits of integer or fraction           Ee  -    1-2   0-9            Optional exponent 0-29 for scientific notation                                         No trailing content      This tries to avoid some scenarios  just in case    Overflowing any buffers the original string might get passed to   Slowness or oddities caused by denormal numbers like 1E-323  Passing Infinity when a finite number is expected  try 1E309 or -1E309

User · Answer

This one will allow also for signed and float numbers or empty string   var reg     -  d     d      If you don t want allow to empty string use this one   var reg     -  d     d

User · Answer

0-9         is a regular expression matching any single digit  so 1 will return true but 123 will return false   If you add the   quantifier     0-9      the expression will match arbitrary length strings of digits and 123 will return true    123f will still return false    Be aware that technically an empty string is a 0-length string of digits  and so it will return true using   0-9     If you want to only accept strings containing 1 or more digits  use   instead of      0-9      As the many others have pointed out  there are more than a few ways to achieve this  but I felt like it was appropriate to point out that the code in the original question only requires a single additional character to work as intended

User · Answer

I see you have already gotten a lot of answers  but if you are looking for a regular expression that can match integers and floating point numbers  this one will work for you   var reg     -  d     d

User · Answer

Why dont use something like     isNumeric   input  val      Is jquery tested  and the most common case are checked

User · Answer

var validation         isEmailAddress function str            var pattern     w     -   w     w     -   w       w 2 3               return pattern test str       returns a boolean            isNotEmpty function  str            var pattern    S            return pattern test str       returns a boolean            isNumber function str            var pattern      d             return pattern test str       returns a boolean            isSame function str1 str2           return str1     str2               alert validation isNotEmpty  dff     alert validation isNumber 44    alert validation isEmailAddress  mf tl ff     alert validation isSame  sf   sf

User · Answer

This function checks if it s input is numeric in the classical sense  as one expects a normal number detection function to work    It s a test one can use for HTML form input  for example    It bypasses all the JS folklore  like tipeof NaN    number  parseint  1 Kg     1  booleans coerced into numbers  and the like     It does it by rendering the argument as a string and checking that string against a regex like those by  codename- but allowing entries like 5  and  5    function isANumber  n         var numStr     -   d     d      d     d          return numStr test  n toString         not numeric  Logger log   isANumber   aaa         isANumber   aaa       Logger log   isANumber            isANumber          Logger log   isANumber   lkjh         isANumber   lkjh       Logger log   isANumber  0 0        isANumber  0   0      Logger log   isANumber  1 0        isANumber  1   0      Logger log   isANumber   1Kg         isANumber   1Kg       Logger log   isANumber   1 Kg         isANumber   1 Kg       Logger log   isANumber  false        isANumber  false      Logger log   isANumber  true        isANumber  true       numeric  Logger log   isANumber   0         isANumber   0       Logger log   isANumber   12 5         isANumber   12 5       Logger log   isANumber    5         isANumber    5       Logger log   isANumber   5          isANumber   5        Logger log   isANumber   -5         isANumber   -5       Logger log   isANumber   -5          isANumber   -5        Logger log   isANumber   - 5         isANumber   -5        Logger log   isANumber   1234567890         isANumber   1234567890        Explanation of the regex       -   d     d      d     d         The initial     and the final     match the start and the end of the string  to ensure the check spans the whole string  The  -   part is the minus sign with the     multiplier that allows zero or one instance of it   Then there are two similar groups  delimited by parenthesis  The string has to match either of these groups  The first matches numbers like 5  and the second  5  The first group is     d     d    The   d   matches a digit   d  one or more times  The       is the decimal point  escaped with     to devoid it of its magic   zero or one times    The last part   d   is again a digit  zero or more times  All the parts are optional but the first digit  so this group matches numbers like 5  and not  5 which are matched by the other half

User · Answer

-   d     d     Ee     -   d

User · Answer

This is extreme overkill for your purpose  but here s what I use   var numberReSnippet       NaN -         d    d      d      E e    -    d    Infinity     var matchOnlyNumberRe   new RegExp       numberReSnippet            To my knowledge  this matches all the variations on numbers that Java and JavaScript will ever throw at you  including  -Infinity    1e-24  and  NaN    It also matches numbers you might type  such as  - 5    As written  reSnippet is designed to be dropped into other regular expressions  so you can extract  or avoid  numbers  Despite all the parentheses  it contains no capturing groups   Thus  matchOnlyNumberRe  matches only strings that are numbers  and has a capturing group for the entire string   Here are the Jasmine tests  so you can see what it does and doesn t handle   describe  Number Regex   function         var re   new RegExp       numberReSnippet              it  Matches Java and JavaScript numbers   function             expect re test           1    toBe true           expect re test         0 2    toBe true           expect re test       0 4E4    toBe true       Java-style         expect re test         -55    toBe true           expect re test        -0 6    toBe true           expect re test    -0 77E77    toBe true           expect re test        88E8    toBe true           expect re test         NaN    toBe true           expect re test    Infinity    toBe true           expect re test   -Infinity    toBe true           expect re test       1e 24    toBe true       JavaScript-style             it  Matches fractions with a leading decimal point   function             expect re test           3    toBe true           expect re test         - 3    toBe true           expect re test        3e-4    toBe true               it  Doesn t match non-numbers   function             expect re test                toBe false           expect re test          9     toBe false           expect re test                toBe false           expect re test           E    toBe false           expect re test         e24    toBe false           expect re test     1e 24 5    toBe false           expect re test  - Infinity    toBe false

User · Answer

On input  if you want to filter out other characters and only show numbers in the input field  you could replace the value of the field on keyup       var yourInput   jQuery   input-field        yourInput keyup function             yourInput val  yourInput val   replace     d  g

User · Answer

As you said  you want hash to contain only numbers   var reg   new RegExp    0-9         or   var reg   new RegExp     d         d and  0-9  both mean the same thing  The   used means that search for one or more occurring of  0-9

User · Answer

Maybe it works   let a    1234  parseInt a     a    true let b    1234abc  parseInt b     b    false

User · Answer

Simple Regex javascript   var cnpj    12 32 432 1-22   var rCnpj   cnpj replace   D gm      console log cnpj      Result    1232432122   Checks for only numbers   if rCnpj     cnpj      return true      Simple example   if  12 32 432 1-22  replace   D gm     length  gt  0      console log  Ok

User · Answer

If you need just positive integer numbers and don t need leading zeros  e g   0001234  or  00     var reg         1-9  d   d

User · Answer

Number only regex  Updated    var reg   new RegExp    0-9    g

User · Answer

d will not match the decimal point  Use the following for the decimal   const re      d     d       123  match re           true  123 3  match re         true  123 3  match re         false

User · Answer

If you want to match the numbers with signed values  you can use   var reg   new RegExp     -       d        It will validate the numbers of format   1  -1  1

User · Answer

You could also use the following methods but be aware of their internal implementation and or return values   1A isNaN   13761123123123       returns true 1B isNaN   13761123123ABC       returns false  2A    1 23      returns 1 2B    1 2A      returns 0   For 1A  amp  1B the string is first type coerced using the   operator before being passed to the isNaN   function  This works because a number types that include non-numeric values return NaN  There are considerations with the isNaN   s implementation details which is documented here  One consideration is if a boolean value is passed as isNaN  false true  are coerced to their numeric equivalents and thus false is returned but one might expect the function to return true since the boolean value isn t numeric in the sense of what we are testing   For 2A  amp  2B it s worth noting that finding the complement of the number requires the given value in question to be within the range the values of a signed 32 bit integer which can be referenced in the spec   My personal preference  although it could be argued to be less readable since they include the unary operator  is 1A  amp  1B because of the speed and conciseness   Perf https   jsperf com numeric-string-test-regexvsisnan 1

User · Answer

var pattern     0-9        amp      -       This tries to avoid some scenarios  just in case   Overflowing any buffers the original string might get passed to  Slowness or oddities caused by denormal numbers like 1E-323  Passing Infinity when a finite number is expected  try 1E309 or -1E309

User · Answer

var reg      d       should do it   The original matches anything that consists of exactly one digit

[javascript] Regex to check whether a string contains only numbers

Examples related to javascript

Examples related to regex