Is there a splice method for strings

Question

The Javascript splice only works with arrays  Is there similar method for strings  Or should I create my own custom function   The substr    and substring   methods will only return the extracted string and not modify the original string  What I want to do is remove some part from my string and apply the change to the original string  Moreover  the method replace   will not work in my case because I want to remove parts starting from an index and ending at some other index  exactly like what I can do with the splice   method  I tried converting my string to an array  but this is not a neat method

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I solved my problem using this code  is a somewhat replacement for the missing splice   let str    I need to remove a character from this   let pos   str indexOf  character    if pos gt -1     let result   str slice 0  pos-2    str slice pos  str length     console log result    I need to remove character from this      I needed to remove a character before after a certain word  after you get the position the string is split in two and then recomposed by flexibly removing characters using an offset along pos

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Here s a nice little Curry which lends better readability  IMHO    The second function s signature is identical to the Array prototype splice method   function mutate s        return function splice             var a   s split              Array prototype splice apply a  arguments           return a join                mutate  101   1  1   1      I know there s already an accepted answer  but hope this is useful

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Edit This is of course not the best way to  quot splice quot  a string  I had given this as an example of how the implementation would be  which is flawed and very evident from a split    splice   and join    For a far better implementation  see Louis s method   No  there is no such thing as a String splice  but you can try this  newStr   str split         or newStr       str   newStr splice 2 5   newStr   newStr join       I realise there is no splice function as in Arrays  so you have to convert the string into an array  Hard luck

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Simply use substr for string  ex    var str    Hello world    var res   str substr 1  str length     Result   ello world

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There seem to be a lot of confusion which was addressed only in comments by elclanrs and raina77ow  so let me post a clarifying answer   Clarification  From  string splice  one may expect that it  like the one for arrays    accepts up to 3 arguments  start position  length and  optionally  insertion  string  returns the cut out part modifies the original string   The problem is  the 3d requirement can not be fulfilled because strings are immutable  related  1  2   I ve found the most dedicated comment here      In JavaScript strings are primitive value types and not objects  spec   In fact  as of ES5  they re one of the only 5 value types alongside null  undefined  number and boolean  Strings are assigned by value and not by reference and are passed as such  Thus  strings are not just immutable  they are a value  Changing the string  hello  to be  world  is like deciding that from now on the number 3 is the number 4    it makes no sense    So  with that in account  one may expect the  string splice  thing to only    accepts up to 2 arguments  start position  length  insertion makes no sense since the string is not changed  returns the cut out part   which is what substr does  or  alternatively    accepts up to 3 arguments  start position  length and  optionally  insertion  string  returns the modified string  without the cut part and with insertion    which is the subject of the next section   Solutions  If you care about optimizing  you should probably use the Mike s implementation   String prototype splice   function index  count  add        if  index  lt  0            index    this length          if  index  lt  0              index   0            return this slice 0  index     add          this slice index   count       Treating the out-of-boundaries index may vary  though  Depending on your needs  you may want       if  index  lt  0            index    this length          if  index  lt  0              index   0            if  index  gt   this length            index -  this length          if  index  gt   this length              index   this length - 1          or even      index   index   this length      if  index  lt  0          index   this length   index    If you don t care about performance  you may want to adapt Kumar s suggestion which is more straight-forward   String prototype splice   function index  count  add        var chars   this split          chars splice index  count  add       return chars join          Performance  The difference in performances increases drastically with the length of the string  jsperf shows  that for strings with the length of 10 the latter solution  splitting  amp  joining  is twice slower than the former solution  using slice   for 100-letter strings it s x5 and for 1000-letter strings it s x50  in Ops sec it s                         10 letters   100 letters   1000 letters slice implementation    1 25 M       2 00 M         1 91 M split implementation    0 63 M       0 22 M         0 04 M   note that I ve changed the 1st and 2d arguments when moving from 10 letters to 100 letters  still I m surprised that the test for 100 letters runs faster than that for 10 letters

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It is faster to slice the string twice  like this   function spliceSlice str  index  count  add         We cannot pass negative indexes directly to the 2nd slicing operation    if  index  lt  0        index   str length   index      if  index  lt  0          index   0               return str slice 0  index     add          str slice index   count       than using a split followed by a join  Kumar Harsh s method   like this   function spliceSplit str  index  count  add      var ar   str split        ar splice index  count  add     return ar join          Here s a jsperf that compares the two and a couple other methods   jsperf has been down for a few months now  Please suggest alternatives in comments    Although the code above implements functions that reproduce the general functionality of splice  optimizing the code for the case presented by the asker  that is  adding nothing to the modified string  does not change the relative performance of the various methods

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Louis s spliceSlice method fails when add value is 0 or other falsy values  here is a fix    function spliceSlice str  index  count  add      if  index  lt  0        index   str length   index      if  index  lt  0          index   0              const hasAdd   typeof add      undefined     return str slice 0  index     hasAdd   add         str slice index   count

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The method Louis s answer  as a String prototype function   String prototype splice   function index  count  add      if  index  lt  0        index   this length   index      if  index  lt  0          index   0              return this slice 0  index     add          this slice index   count       Example     gt   Held   splice 3 0  lo Worl     lt   Hello World

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I would like to offer a simpler alternative to both the Kumar Cody and the Louis methods   On all the tests I ran  it performs as fast as the Louis method   see fiddle tests for benchmarks      String prototype splice   function startIndex length insertString       return this substring 0 startIndex    insertString   this substring startIndex   length        You can use it like this   var creditCardNumber    5500000000000004   var cardSuffix   creditCardNumber splice 0 12          console log cardSuffix       output      0004   See Test Results  https   jsfiddle net 0quz9q9m 5

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So  whatever adding splice method to a String prototype cant work transparent to spec     Let s do some one extend it   String prototype splice   function    a       for var r       p   0  i   1  i  lt  a length  i  3          r   this slice p  p a i-1      a i 1         this slice p a i   p a i 2   this length       return r       Every 3 args group  inserting  in splice style  Special if there is more then one 3 args group  the end off each cut will be the start of next     0123456789  splice 4 1  fourth  8 1  eighth      return  0123fourth567eighth9   You can drop or zeroing the last arg in each group  that treated as  nothing to insert      0123456789  splice -4 2     return  0123459   You can drop all except 1st arg in last group  that treated as  cut all after 1st arg position      0123456789  splice 0 2 null 3 1 null 5 2     8     return  24 7   if You pass multiple  you MUST check the sort of the positions left-to-right order by youreself  And if you dont want you MUST DO NOT use it like this     0123456789  splice 4 -3  what       return  0123what 123456789

[javascript] Is there a splice method for strings?

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