How to count string occurrence in string

Question

How can I count the number of times a particular string occurs in another string  For example  this is what I am trying to do in Javascript   var temp    This is a string    alert temp count  is       should output  2

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substr count translated to Javascript from php     Locutus  Package that translates Php to JS  substr count  official page  code copied below    function substr count  haystack  needle  offset  length          eslint-disable-line camelcase       discuss at  https   locutus io php substr count       original by  Kevin van Zonneveld  https   kvz io       bugfixed by  Onno Marsman  https   twitter com onnomarsman       improved by  Brett Zamir  https   brett-zamir me       improved by  Thomas        example 1  substr count  Kevin van Zonneveld    e          returns 1  3        example 2  substr count  Kevin van Zonneveld    K   1         returns 2  0        example 3  substr count  Kevin van Zonneveld    Z   0  10         returns 3  false    var cnt   0    haystack         needle         if  isNaN offset         offset   0       if  isNaN length         length   0       if  needle length     0        return false       offset--    while   offset   haystack indexOf needle  offset   1       -1        if  length  gt  0  amp  amp   offset   needle length   gt  length          return false           cnt          return cnt     Check out Locutus s Translation Of Php s substr count function

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My solution    x000D   x000D  var temp    This is a string    x000D   x000D  function countOcurrences str  value    x000D    var regExp   new RegExp value   gi    x000D    return  str match regExp         length  x000D    x000D   x000D  console log countOcurrences temp   is     x000D   x000D   x000D

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Here is the fastest function   Why is it faster    Doesn t check char by char  with 1 exception  Uses a while and increments 1 var  the char count var  vs  a for loop checking the length and incrementing 2 vars  usually var i and a var with the char count  Uses WAY less vars Doesn t use regex  Uses an  hopefully  highly optimized function All operations are as combined as they can be  avoiding slowdowns due to multiple operations  String prototype timesCharExist function c  var t 0 l 0 c  c     0  while l this indexOf c l  1   t return t      Here is a slower and more readable version       String prototype timesCharExist   function   chr             var total   0  last location   0  single char     chr        0           while  last location   this indexOf  single char  last location     1                         total   total   1                    return total           This one is slower because of the counter  long var names and misuse of 1 var   To use it  you simply do this        The char  a  only shows up twice  timesCharExist  a      Edit   2013 12 16   DON T use with Opera 12 16 or older  it will take almost 2 5x more than the regex solution   On chrome  this solution will take between 14ms and 20ms for 1 000 000 characters   The regex solution takes 11-14ms for the same amount   Using a function  outside String prototype  will take about 10-13ms   Here is the code used       String prototype timesCharExist function c  var t 0 l 0 c  c     0  while l this indexOf c l  1   t return t        var x Array 100001  join  1234567890         console time  proto   x timesCharExist  1   console timeEnd  proto         console time  regex   x match  1 g  length console timeEnd  regex         var timesCharExist function x c  var t 0 l 0 c  c     0  while l x indexOf c l  1   t return t         console time  func   timesCharExist x  1   console timeEnd  func      The result of all the solutions should be 100 000   Note  if you want this function to count more than 1 char  change where is c  c     0  into c c

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The non-regex version    x000D   x000D   var string    This is a string   x000D      searchFor    is   x000D      count   0  x000D      pos   string indexOf searchFor   x000D   x000D  while  pos  gt  -1    x000D        count  x000D      pos   string indexOf searchFor    pos   x000D    x000D   x000D  console log count        2 x000D   x000D   x000D

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ES2020 offers a new MatchAll which might be of use in this particular context  Here we create a new RegExp  please ensure you pass  g  into the function  Convert the result using Array from and count the length  which returns 2 as per the original requestor s desired output   x000D   x000D  let strToCheck   RegExp  is    g   let matchesReg    This is a string   matchAll strToCheck  console log Array from matchesReg  length     2 x000D   x000D   x000D

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Now this is a very old thread i ve come across but as many have pushed their answer s  here is mine in a hope to help someone with this simple code    x000D   x000D  var search value    This is a dummy sentence    x000D  var letter    a     Can take any letter  have put in a var if anyone wants to use this variable dynamically   x000D  letter   letter  amp  amp   string      typeof letter   letter       x000D  var count  x000D  for  var i   count   0  i  lt  search value length  count     search value i       letter    x000D  console log count   x000D   x000D   x000D    I m not sure if it is the fastest solution but i preferred it for simplicity and for not using regex  i just don t like using them

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x000D   x000D  var countInstances   function body  target    x000D    var globalcounter   0  x000D    var concatstring        x000D    for var i 0 j target length i lt body length i     x000D      concatstring   body substring i-1 j   x000D       x000D      if concatstring     target   x000D         globalcounter    1  x000D         concatstring       x000D        x000D      x000D     x000D     x000D    return globalcounter  x000D    x000D     x000D   x000D  console log    countInstances  abcabc    abc              gt  2 x000D  console log    countInstances  ababa    aba              gt  2 x000D  console log    countInstances  aaabbb    ab              gt  1 x000D   x000D   x000D

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No one will ever see this  but it s good to bring back recursion and arrow functions once in a while  pun gloriously intended   String prototype occurrencesOf   function s  i     return  n   gt   n     -1    0   1   this occurrencesOf s  n   1   this indexOf s   i    0

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Simple version without regex    x000D   x000D  var temp    This is a string    x000D   x000D  var count    temp split  is   length - 1   x000D   x000D  alert count   x000D   x000D   x000D

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You can try this    x000D   x000D  var theString    This is a string    x000D  console log theString split  is   length - 1   x000D   x000D   x000D

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You can use match to define such function   String prototype count   function search        var m   this match new RegExp search toString   replace                          g          g         return m   m length 0

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The g in the regular expression  short for global  says to search the whole string rather than just find the first occurrence  This matches is twice    x000D   x000D  var temp    This is a string    x000D  var count    temp match  is g         length  x000D  console log count   x000D   x000D   x000D    And  if there are no matches  it returns 0    x000D   x000D  var temp    Hello World    x000D  var count    temp match  is g         length  x000D  console log count   x000D   x000D   x000D

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x000D   x000D  var str    stackoverflow   var arr   Array from str   console log arr    for  let a   0  a  lt   arr length  a        var temp   arr a     var c   0    for  let b   0  b  lt   arr length  b          if  temp     arr b           c                 console log  the   arr a   is counted for   c      x000D   x000D   x000D

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You could try this let count   s length - s replace  is g   quot  quot   length

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Try this   function countString str  search       var count 0      var index str indexOf search       while index  -1           count            index str indexOf search index 1             return count

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Super duper old  but I needed to do something like this today and only thought to check SO afterwards  Works pretty fast for me   String prototype count   function substr start overlap        overlap   overlap    false      start   start    0       var count   0           offset   overlap   1   substr length       while  start   this indexOf substr  start    offset       offset - 1             count      return count

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function substrCount  str  x        let count   -1  pos   0     do        pos   str indexOf  x  pos     1       count         while  pos  gt  0       return count

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Just code-golfing Rebecca Chernoff s solution  -   alert   This is a string   match  is g         length

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I think the purpose for regex is much different from indexOf  indexOf simply find the occurance of a certain string while in regex you can use wildcards like  A-Z  which means it will find any capital character in the word without stating the actual character   Example    x000D   x000D   var index    This is a string  indexOf  is    x000D   console log index   x000D   var length    This is a string  match   a-z  g  length  x000D      where  a-z  is a regex wildcard expression thats why its slower x000D   console log length   x000D   x000D   x000D

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x000D   x000D  String prototype Count   function  find    x000D      return this split find  length - 1  x000D    x000D   x000D  console log  This is a string   Count  is     x000D   x000D   x000D    This will return 2

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function countInstances string  word       return string split word  length - 1

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x000D   x000D  var temp    This is a string    x000D  console log  temp match new RegExp  is    g           length   x000D   x000D   x000D

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The parameters  ustring  the superset string countChar  the substring A function to count substring occurrence in JavaScript   x000D   x000D  function subStringCount ustring  countChar     var correspCount   0    var corresp   false    var amount   0    var prevChar   null      for var i 0  i  ustring length  i           if ustring charAt i     countChar charAt 0   amp  amp  corresp    false          corresp   true         correspCount    1         if correspCount    countChar length            amount  1           corresp   false           correspCount   0                  prevChar   1              else if ustring charAt i     countChar charAt prevChar   amp  amp  corresp    true          correspCount    1         if correspCount    countChar length            amount  1           corresp   false           correspCount   0           prevChar   null          else           prevChar    1                  else         corresp   false         correspCount   0              return amount     console log subStringCount  Hello World  Hello World    ll     x000D   x000D   x000D

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Try it   lt  php   str    33 33 56 89 56 56   echo substr count  str   56      gt    lt script type  text javascript  gt  var temp    33 33 56 89 56 56   var count   temp match  56 g     alert count length    lt  script gt

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Answer for Leandro Batista   just a problem with the regex expression    x000D   x000D    use strict   x000D   var dataFromDB    testal   x000D    x000D       input name  tbInput     on  change  function    x000D   var charToTest     this  val    x000D   var howManyChars   charToTest length  x000D   var nrMatches   0  x000D   if howManyChars     0   x000D    charToTest   charToTest charAt 0   x000D    var regexp   new RegExp charToTest  gi    x000D    var arrMatches   dataFromDB match regexp   x000D    nrMatches   arrMatches   arrMatches length   0  x000D     x000D        result   html nrMatches toString     x000D   x000D        x000D   lt script src  https   ajax googleapis com ajax libs jquery 2 1 1 jquery min js  gt  lt  script gt  x000D   lt div class  main  gt  x000D  What do you wanna count  lt input type  text  name  tbInput  value    gt  lt br   gt  x000D  Number of occurences    lt span id  result  gt 0 lt  span gt  x000D   lt  div gt  x000D   x000D   x000D

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var myString    This is a string            var foundAtPosition   0          var Count   0          while  foundAtPosition    -1                        foundAtPosition   myString indexOf  is  foundAtPosition               if  foundAtPosition    -1                                Count                    foundAtPosition                                    document write  There are     Count     occurrences of the word IS      Refer  - count a substring appears in the string for step by step explanation

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For anyone that finds this thread in the future  note that the accepted answer will not always return the correct value if you generalize it  since it will choke on regex operators like   and    Here s a better version  that can handle any needle   function occurrences  haystack  needle      var  needle   needle      replace     g              replace     g           return       haystack match new RegExp        needle         g              length

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Function that count occurrences of a substring in a string      param  String  string               The string     param  String  subString            The sub string to search for     param  Boolean   allowOverlapping   Optional   Default false         author Vitim us https   gist github com victornpb 7736865     see Unit Test https   jsfiddle net Victornpb 5axuh96u      see http   stackoverflow com questions 4009756 how-to-count-string-occurrence-in-string 7924240 7924240     function occurrences string  subString  allowOverlapping         string            subString            if  subString length  lt   0  return  string length   1        var n   0          pos   0          step   allowOverlapping   1   subString length       while  true            pos   string indexOf subString  pos           if  pos  gt   0                  n              pos    step            else break            return n      Usage  occurrences  foofoofoo    bar      0  occurrences  foofoofoo    foo      3  occurrences  foofoofoo    foofoo      1   allowOverlapping  occurrences  foofoofoo    foofoo   true     2   Matches     foofoofoo 1  ----   2     ----     Unit Test   https   jsfiddle net Victornpb 5axuh96u    Benchmark     I ve made a benchmark test and my function is more then 10 times   faster then the regexp match function posted by gumbo  In my test   string is 25 chars length  with 2 occurences of the character  o   I   executed 1 000 000 times in Safari       Safari 5 1      Benchmark  Total time execution  5617 ms  regexp       Benchmark  Total time execution  881 ms   my function 6 4x faster       Firefox 4      Benchmark  Total time execution  8547 ms  Rexexp       Benchmark  Total time execution   634 ms   my function 13 5x faster             Edit  changes I ve made         cached substring length   added type-casting to string    added optional  allowOverlapping  parameter   fixed correct output for    empty substring case       Gist   https   gist github com victornpb 7736865

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came across this post   let str    As sly as a fox  as strong as an ox    let target    as      let s look for it  let pos   0  while  true      let foundPos   str indexOf target  pos     if  foundPos    -1  break     alert   Found at   foundPos        pos   foundPos   1     continue the search from the next position     The same algorithm can be layed out shorter   let str    As sly as a fox  as strong as an ox   let target    as    let pos   -1  while   pos   str indexOf target  pos   1      -1      alert  pos

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Iterate less the second time  just when first letter of substring matches  but still uses 2 for loops     function findSubstringOccurrences str  word            let occurrences   0          for let i 0  i lt str length  i                 if word 0      str i       to make it faster and iterate less                 for let j 0  j lt word length  j                         if str i j      word j   break                      if j     word length - 1  occurrences                                                      return occurrences                 console log findSubstringOccurrences  quot jdlfkfomgkdjfomglo quot    quot omg quot

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Building upon  Vittim us answer above  I like the control his method gives me  making it easy to extend  but I needed to add case insensitivity and limit matches to whole words with support for punctuation   e g   bath  is in  take a bath   but not  bathing    The punctuation regex came from  https   stackoverflow com a 25575009 497745  How can I strip all punctuation from a string in JavaScript using regex    function keywordOccurrences string  subString  allowOverlapping  caseInsensitive  wholeWord         string            subString            if  subString length  lt   0  return  string length   1     deal with empty strings      if caseInsensitive                            string   string toLowerCase            subString   subString toLowerCase               var n   0          pos   0          step   allowOverlapping   1   subString length          stringLength   string length          subStringLength   subString length       while  true                pos   string indexOf subString  pos           if  pos  gt   0                        var matchPos   pos              pos    step    slide forward the position pointer no matter what              if wholeWord    only whole word matches are desired                               if matchPos  gt  0    if the string is not at the very beginning we need to check if the previous character is whitespace                                                               if     s u2000- u206F u2E00- u2E7F         amp         -      lt   gt                 test string matchPos - 1      ignore punctuation                                               continue    then this is not a match                                                          var matchEnd   matchPos   subStringLength                  if matchEnd  lt  stringLength - 1                                                                if      s u2000- u206F u2E00- u2E7F         amp         -      lt   gt                 test string matchEnd      ignore punctuation                                               continue    then this is not a match                                                                      n                            else break            return n      Please feel free to modify and refactor this answer if you spot bugs or improvements

[javascript] How to count string occurrence in string?

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