Does JavaScript have a method like range to generate a range within the supplied bounds

Question

In PHP  you can do     range 1  3      Array 1  2  3  range  A    C       Array  A    B    C     That is  there is a function that lets you get a range of numbers or characters by passing the upper and lower bounds   Is there anything built-in to JavaScript natively for this  If not  how would I implement it

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OK  in JavaScript we don t have a range   function like PHP  so we need to create the function which is quite easy thing  I write couple of one-line functions for you and separate them for Numbers and Alphabets as below   for Numbers   function numberRange  start  end      return new Array end - start  fill   map  d  i    gt  i   start       and call it like   numberRange 5  10      5  6  7  8  9    for Alphabets   function alphabetRange  start  end      return new Array end charCodeAt 0  - start charCodeAt 0   fill   map  d  i    gt  String fromCharCode i   start charCodeAt 0         and call it like   alphabetRange  c    h        c    d    e    f    g

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Keeping it simple      Generator function  iter a  b  step   1      for  let i   b   a   0  i  lt   b    a   i    step        yield i        const range    a  b  step   1    gt    typeof a      string            iter a charCodeAt    b charCodeAt     1   map n   gt  String fromCharCode n             iter a  b  step    range 4      0  1  2  3  range 1  4      1  2  3  range 2  20  3      2  5  8  11  14  17  range  A    C        A    B    C

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you can use lodash function   range 10  https   lodash com docs range

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A rather minimalistic implementation that heavily employs ES6 can be created as follows  drawing particular attention to the Array from   static method   const getRange    start  stop    gt  Array from    new Array  stop - start    1         i    gt  i   start

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Here is a definition of a range function that behaves exactly like Python s range type except that this one is not lazy  It should be easy to turn it into a generator   The arguments to the range constructor must be numbers  If the step argument is omitted  it defaults to 1  If the start argument is omitted  it defaults to 0  If step is zero  an error is raised   range    start  stop  step 1    gt        if step     0  throw new Error  range   arg 3 must not be zero         const noStart   stop    null      stop   noStart   start   stop      start   noStart   0   start      const length   Math ceil   stop - start    step         return Array from  length       i    gt   i   step    start      console log range -10  10  2      output  Array   -10 -8 -6 -4 -2 0 2 4 6 8  console log range 10        Array   0 1 2 3 4 5 6 7 8 9  console log 3  12       Array   3 4 5 6 7 8 9 10 11

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Using Harmony spread operator and arrow functions   var range    start  end    gt      Array end - start   1   map     i    gt  start   i     Example   range 10  15     10  11  12  13  14  15

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Coded to 2010 specs  ya  it is 2016 with ES6 generators   Here s my take  with options to emulate the Python s range   function    Array range   function start  end  step       if  start    undefined    return          undefined  check      if    step     0        return        vs  throw TypeError  Invalid  step  input              step     0  check      if  typeof start     number        number check         if  typeof end     undefined        single argument input             end   start              start   0              step   1                    if    step      typeof step     number                step   end  lt  start   -1   1                     var length   Math max Math ceil  end - start    step   0           var out   Array length            for  var idx   0  idx  lt  length  idx    start    step              out idx    start                        Uncomment to check  end  in range   output  non pythonic         if    out out length-1    step     end         end  check             out push end                   else               Historical    amp   is the 27th letter  http   nowiknow com and-the-27th-letter-of-the-alphabet             Axiom   a   lt   z  and  z   lt   A             note   a   gt   A     true   small a  gt  big A   try explaining it to a kid             var st    abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ amp       axiom ordering          if  typeof end     undefined        single argument input             end   start              start    a                      var first   st indexOf start           var last   st indexOf end            if    step      typeof step     number                step   last  lt  first   -1   1                     if   first    -1      last    -1         check  first   amp   last              return                       var length   Math max Math ceil  last - first    step   0           var out   Array length            for  var idx   0  idx  lt  length  idx    first    step              out idx    st first                          Uncomment to check  end  in range   output  non pythonic         if    st indexOf out out length-1     step      last         end  check             out push end                      return out      Example   Array range 5             0 1 2 3 4 5  Array range 4 -4 -2       4  2  0  -2  -4  Array range  a   d         a    b    c    d   Array range  B   y         B    A    z    y    different from chr   ordering Array range  f             a    b    c    d    e    f   Array range -5               similar to python Array range -5 0          -5 -4- -3- -2 -1 0

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Solution     best performance var range   function start  stop  step        var a    start       while  start  lt  stop            start    step    1          a push start             return a        or var range   function start  end        return Array   end-start  join 0  split 0  map function n  i            return i start

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Complete ES6 implementation using range  start   stop   step   signature   function range start  stop  step 1     if  stop  stop start start 0     return Array from new Array int  stop-start  step     x i    gt  start  i step      If you want automatic negative stepping  add  if stop lt start step -Math abs step    Or more minimalistically   range  b  e  step 1   gt     if  e  e b b 0    return Array from new Array int  e-b  step       i    gt  b lt e  b i step   b-i step      If you have huge ranges look at Paolo Moretti s generator approach

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You can use following one-liner to keep things short and simple   x000D   x000D  var start   4  x000D  var end   20  x000D  console log Array end - start   1  fill start  map  x  y    gt  x   y    x000D   x000D   x000D

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An interesting challenge would be to write the shortest function to do this   Recursion to the rescue   function r a b  return a gt b     a  concat r   a b      Tends to be slow on large ranges  but luckily quantum computers are just around the corner   An added bonus is that it s obfuscatory   Because we all know how important it is to hide our code from prying eyes   To truly and utterly obfuscate the function  do this   function r a b  return  a lt b  a b  concat r   a --b   a gt b     a   sort function a b  return a-b

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My codegolfing coworker came up with this  ES6   inclusive     s f   gt     Array f-s 1   map  e i   gt i s    non inclusive    s f   gt     Array f-s   map  e i   gt i s

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I would like to add what I would think is a very adjustable version  which is very fast    const range    start  end    gt        let all           if  typeof start      string   amp  amp  typeof end      string                Return the range of characters using utf-8 least to greatest         const s   start charCodeAt 0           const e   end charCodeAt 0           for  let i   s  i  lt   e  i                  all push String fromCharCode i                    else if  typeof start      number   amp  amp  typeof end      number                Return the range of numbers from least to greatest         for let i   end  i  gt   start  i--                all push i                   else           throw new Error  Did not supply matching types number or string               return all       usage const aTod   range  a    d      Also Typescript if you would like  const range    start  string   number  end  string   number   string     number     gt        const all  string     number             if  typeof start      string   amp  amp  typeof end      string             const s  number   start charCodeAt 0           const e  number   end charCodeAt 0           for  let i   s  i  lt   e  i                  all push String fromCharCode i                    else if  typeof start      number   amp  amp  typeof end      number             for  let i   end  i  gt   start  i--                all push i                   else           throw new Error  Did not supply matching types number or string               return all       Usage const negTenToten  number     range -10  10  as number      Made with some influence from other answers  User is gone now

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Here is my solution that mimics Python  At the bottom you can find some examples how to use it  It works with numbers  just like Python s range   var assert   require  assert          if you use Node  otherwise remove the asserts  var L             L  i e   list      range start  end  step  L range   function  a  b  c        assert arguments length  gt   1  amp  amp  arguments length  lt   3       if  arguments length     3            assert c    0              var li               i          start  end  step          up   true        Increasing or decreasing order  Default  increasing       if  arguments length     1            start   0          end   a          step   1             if  arguments length     2            start   a          end   b          step   1             if  arguments length     3            start   a          end   b          step   c          if  c  lt  0                up   false                       if  up            for  i   start  i  lt  end  i    step                li push i                   else           for  i   start  i  gt  end  i    step                li push i                        return li      Examples      range L range 0  - gt     L range 1  - gt   0  L range 2  - gt   0  1  L range 5  - gt   0  1  2  3  4   L range 1  5  - gt   1  2  3  4  L range 6  4  - gt     L range -2  2  - gt   -2  -1  0  1   L range 1  5  1  - gt   1  2  3  4  L range 0  10  2  - gt   0  2  4  6  8  L range 10  2  -1  - gt   10  9  8  7  6  5  4  3  L range 10  2  -2  - gt   10  8  6  4

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There isn t a native method  But you can do it with filter method of Array    x000D   x000D  var range    array  start  end    gt  x000D        array filter  element  index   gt index gt  start  amp  amp  index  lt   end  x000D   x000D   x000D  alert  range   a   h   e   l   l   o   s   1 5    x000D       h   e   l   l   o   x000D   x000D   x000D

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Using Harmony generators  supported by all browsers except IE11   var take   function  amount  generator        var a            try           while  amount                a push generator next                 amount -  1                  catch  e          return a      var takeAll   function  gen        var a               x       try           do               x   a push gen next               while  x         catch  e          return a      var range    function  d        var unlimited    typeof d to      undefined         if  typeof d from      undefined             d from   0             if  typeof d step      undefined             if  unlimited                d step   1                  else           if  typeof d from      string                 if  d from  lt  d to                    d step   1                else                   d step   -1                          else               if  d from charCodeAt 0   lt  d to charCodeAt 0                     d step   1                else                   d step   -1                                     if  typeof d from      string             for  let i   d from charCodeAt 0    d step  gt  0     unlimited   true   i  lt   d to charCodeAt 0      i  gt   d to charCodeAt 0    i    d step                yield String fromCharCode i                   else           for  let i   d from   d step  gt  0     unlimited   true   i  lt   d to     i  gt   d to   i    d step                yield i                        Examples  take  Example 1   take only takes as much as it can get  take 10  range   from  100  step  5  to  120        returns    100  105  110  115  120   Example 2   to not neccesary  take 10  range   from  100  step  5       returns   100  105  110  115  120  125  130  135  140  145   takeAll  Example 3   from not neccesary  takeAll  range   to  5       returns   0  1  2  3  4  5   Example 4   takeAll  range   to  500  step  100       returns   0  100  200  300  400  500   Example 5   takeAll  range   from   z   to   a        returns     z    y    x    w    v    u    t    s    r    q    p    o    n    m    l    k    j    i    h    g    f    e    d    c    b    a

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It works for characters and numbers  going forwards or backwards with an optional step   var range   function start  end  step        var range           var typeofStart   typeof start      var typeofEnd   typeof end       if  step     0            throw TypeError  Step cannot be zero                if  typeofStart     undefined     typeofEnd     undefined             throw TypeError  Must pass start and end arguments           else if  typeofStart    typeofEnd            throw TypeError  Start and end arguments must be of same type                typeof step     undefined   amp  amp   step   1        if  end  lt  start            step   -step             if  typeofStart     number              while  step  gt  0   end  gt   start   end  lt   start                range push start               start    step                   else if  typeofStart     string              if  start length    1    end length    1                throw TypeError  Only strings with one character are supported                        start   start charCodeAt 0           end   end charCodeAt 0            while  step  gt  0   end  gt   start   end  lt   start                range push String fromCharCode start                start    step                   else           throw TypeError  Only string and number types are supported               return range       jsFiddle   If augmenting native types is your thing  then assign it to Array range    x000D   x000D  var range   function start  end  step    x000D      var range       x000D      var typeofStart   typeof start  x000D      var typeofEnd   typeof end  x000D   x000D      if  step     0    x000D          throw TypeError  Step cannot be zero     x000D        x000D   x000D      if  typeofStart     undefined     typeofEnd     undefined     x000D          throw TypeError  Must pass start and end arguments     x000D        else if  typeofStart    typeofEnd    x000D          throw TypeError  Start and end arguments must be of same type     x000D        x000D   x000D      typeof step     undefined   amp  amp   step   1   x000D   x000D      if  end  lt  start    x000D          step   -step  x000D        x000D   x000D      if  typeofStart     number     x000D   x000D          while  step  gt  0   end  gt   start   end  lt   start    x000D              range push start   x000D              start    step  x000D            x000D   x000D        else if  typeofStart     string     x000D   x000D          if  start length    1    end length    1    x000D              throw TypeError  Only strings with one character are supported     x000D            x000D   x000D          start   start charCodeAt 0   x000D          end   end charCodeAt 0   x000D   x000D          while  step  gt  0   end  gt   start   end  lt   start    x000D              range push String fromCharCode start    x000D              start    step  x000D            x000D   x000D        else   x000D          throw TypeError  Only string and number types are supported    x000D        x000D   x000D      return range  x000D   x000D    x000D   x000D  console log range  A    Z   1    x000D  console log range  Z    A   1    x000D  console log range  A    Z   3    x000D   x000D   x000D  console log range 0  25  1    x000D   x000D  console log range 0  25  5    x000D  console log range 20  5  5    x000D   x000D   x000D

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You can also do the following   const range   Array from Array size   map  el  idx    gt  idx 1  slice begin  end

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Numbers       Array 5  keys        gt   0  1  2  3  4    Character iteration  String fromCharCode        Array  D  charCodeAt 0  -  A  charCodeAt 0    1  keys    map i   gt  i    A  charCodeAt 0        gt   ABCD    Iteration  for  const x of Array 5  keys        console log x  String fromCharCode  A  charCodeAt 0    x         gt  0  A  1  B  2  C  3  D  4  E    As functions  function range size  startAt   0        return     Array size  keys    map i   gt  i   startAt      function characterRange startChar  endChar        return String fromCharCode    range endChar charCodeAt 0  -             startChar charCodeAt 0   startChar charCodeAt 0        As typed functions  function range size number  startAt number   0  ReadonlyArray lt number gt        return     Array size  keys    map i   gt  i   startAt      function characterRange startChar string  endChar string  ReadonlyArray lt string gt        return String fromCharCode    range endChar charCodeAt 0  -             startChar charCodeAt 0   startChar charCodeAt 0        lodash js   range   function    range 10      gt   0  1  2  3  4  5  6  7  8  9    range 1  11      gt   1  2  3  4  5  6  7  8  9  10    range 0  30  5      gt   0  5  10  15  20  25    range 0  -10  -1      gt   0  -1  -2  -3  -4  -5  -6  -7  -8  -9  String fromCharCode      range  A  charCodeAt 0    D  charCodeAt 0    1       gt   ABCD    Old non es6 browsers without a library    Array apply null  Array 5   map function     i   return i        gt   0  1  2  3  4     x000D   x000D  console log     Array 5  keys      x000D   x000D   x000D     ES6 credit to nils petersohn and other commenters

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My personal favorite  const range    start  end    gt  new Array end-start 1  map  el  ind    gt  ind   start

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Here is a simple approach based on  benmcdonald and others  more than one line though      x000D   x000D  let K       x000D  for  i    A  charCodeAt 0   i  lt    Z  charCodeAt 0   i      x000D    K push String fromCharCode i   x000D     x000D  console log K   x000D   x000D   x000D

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Though this is not from PHP  but an imitation of range from Python   function range start  end        var total            if   end            end   start          start   0             for  var i   start  i  lt  end  i    1            total push i              return total     console log range 10        0  1  2  3  4  5  6  7  8  9   console log range 0  10        0  1  2  3  4  5  6  7  8  9  console log range 5  10        5  6  7  8  9

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You can use a function with an array  a for loop  and a Math random   variable to solve that  The for loop pushes numbers into the array  which will contain all the numbers in your range  Then the Math random   randomly selects one  based on the array s length   function randNumInRange min  max      var range        for var count   min  count  lt   max  count          range push count         var randNum   Math floor Math random     range length     alert range randNum

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Did some research on some various Range Functions  Checkout the jsperf comparison of the different ways to do these functions  Certainly not a perfect or exhaustive list  but should help     The Winner is     function range lowEnd highEnd       var arr           c   highEnd - lowEnd   1      while   c--             arr c    highEnd--           return arr    range 0 31     Technically its not the fastest on firefox  but crazy speed difference  imho  on chrome makes up for it   Also interesting observation is how much faster chrome is with these array functions than firefox  Chrome is at least 4 or 5 times faster

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--- UPDATE  Thanks to  lokhmakov for simplification  ---  Another version using ES6 generators   see great Paolo Moretti answer with ES6 generators     const RANGE    x y    gt  Array from  function       while  x  lt   y  yield x            console log RANGE 3 7          3  4  5  6  7     Or  if we only need iterable  then   const RANGE ITER    x y    gt   function       while  x  lt   y  yield x           for  let n of RANGE ITER 3 7      console log n         3    4    5    6    7   --- ORGINAL code was  ---  const RANGE    a b    gt  Array from  function  x y     while  x  lt   y  yield x       a b      and  const RANGE ITER    a b    gt   function  x y     while  x  lt   y  yield x       a b

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I was surprised to come across this thread and see nothing like my solution  maybe I missed an answer   so here it is  I use a simple range function in ES6 syntax        begin  end  const range    b  e    gt  Array apply null  Array e - b   map     i    gt   return i b       But it works only when counting forward  ie  begin  lt  end   so we can modify it slightly when needed like so     const range    b  e    gt  Array apply null  Array Math abs e - b    map     i    gt   return b  lt  e   i b   b-i

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You can use lodash or Undescore js range   var range   require  lodash range   range 10     - gt    0  1  2  3  4  5  6  7  8  9       Alternatively  if you only need a consecutive range of integers you can do something like   Array apply undefined    length  10    map Number call  Number     - gt    0  1  2  3  4  5  6  7  8  9       In ES6 range can be implemented with generators   function  range start 0  end null  step 1      if  end    null        end   start      start   0         for  let i start  i  lt  end  i  step        yield i          This implementation saves memory when iterating large sequences  because it doesn t have to materialize all values into an array   for  let i of range 1  oneZillion       console log i

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I would code something like this   function range start  end        return Array end-start  join 0  split 0  map function val  id   return id start         range -4 2       -4 -3 -2 -1 0 1   range 3 9       3 4 5 6 7 8    It behaves similarly to Python range    gt  gt  gt  range -4 2   -4  -3  -2  -1  0  1

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Array range   function a  b  step       var A           if typeof a     number            A 0    a          step   step    1          while a step  lt   b               A A length   a   step                      else           var s    abcdefghijklmnopqrstuvwxyz           if a     a toUpperCase                 b   b toUpperCase                s   s toUpperCase                      s   s substring s indexOf a   s indexOf b   1           A   s split                        return A              Array range 0 10       0 1 2 3 4 5 6 7 8 9 10       Array range -100 100 20       -100 -80 -60 -40 -20 0 20 40 60 80 100       Array range  A   F         A   B   C   D   E   F        Array range  m   r         m   n   o   p   q   r

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var range    l r    gt  new Array r - l  fill   map    k    gt  k   l

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I prefer the way below   x000D   x000D  var range   function x  y    x000D      return Array y - x 1  fill x  map  a  b    gt   return a b   filter i   gt  i  gt   x   x000D     x000D  console log range 3  10    x000D   x000D   x000D

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For a more ruby-like approach with good backward compatibility   range  begin   end   0  where begin and end are numbers  var range   function begin  end      if  typeof end      undefined         end   begin  begin   0        var result       modifier   end  gt  begin   1   -1    for   var i   0  i  lt   Math abs end - begin   i           result push begin   i   modifier         return result      Examples   range 3       gt   0  1  2  3  range -2       gt   0  -1  -2  range 1  2      gt   1  2  range 1  -2       gt   1  0  -1  -2

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For numbers you can use ES6 Array from    which works in everything these days except IE  Shorter version  Array from  length  20    x  i    gt  i    Longer version  Array from new Array 20    x  i    gt  i          which creates an array from 0 to 19 inclusive  This can be further shortened to one of these forms  Array from Array 20  keys        or     Array 20  keys      Lower and upper bounds can be specified too  for example  Array from new Array 20    x  i    gt  i    lowerBound     An article describing this in more detail  http   www 2ality com 2014 05 es6-array-methods html

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Use this  It creates an array with given amount of values  undefined   in the following example there are 100 indexes  but it is not relevant as here you need only the keys  It uses in the array  100   1  because the arrays are always 0 index based  So if it s given 100 values to generate  the index starts from 0  hence the last value is always 99 not 100   x000D   x000D  range 2  100    function range start  end        console log     Array end   1  keys    filter value   gt  end  gt   value  amp  amp  start  lt   value       x000D   x000D   x000D

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Here s a nice short way to do it in ES6 with numbers only  don t know its speed compares    Array prototype map call     repeat 1   upper - lower    v  i    gt  i   lower    For a range of single characters  you can slightly modify it   Array prototype map call     repeat 1   upper codePointAt   - lower codePointAt      v  i    gt  String fromCodePoint i   lower codePointAt

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My new favorite form  ES2015   Array 10  fill 1  map  x  y    gt  x   y    And if you need a function with a step param   const range    start  stop  step   1    gt    Array Math ceil  stop - start    step   fill start  map  x  y    gt  x   y   step

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A recursive solution to generating integer array within bounds   function intSequence start  end  n   start  arr           return  n     end    arr concat n        intSequence start  end  start  lt  end   n   1   n - 1  arr concat n         gt  intSequence 1  1   lt - Array   1      gt  intSequence 1  3   lt - Array 3    1  2  3      gt  intSequence 3  -3   lt - Array 7    3  2  1  0  -1  -2  -3

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range                0  10  step 1    range max            0  max  step 1    range min max        min  max  step 1    range min step max   min  max  step step    Use     console log    range 3       Array from range 5          range 100      for  const v of range 1 10           function  range    args        let  min  step  max              0   0  1  10           1   0  args 0   gt   0   1   -1  args 0            2   args 0   args 1   gt   args 0    1   -1  args 1            3  args        args length             if  min     undefined  throw new SyntaxError  Too many arguments        let x   min      while  step  gt   0   x  lt  max   x  gt  max            yield x          x    step         console log    range             0 1 2 3 4 5 6 7 8 9 console log    range 3           0 1 2 console log    range 2  5        2 3 4 console log    range 5  2        5 4 3 console log    range 3  -3       3 2 1 0 -1 -2 console log    range -3  3       -3 -2 -1 0 1 2 console log    range -5  -2      -5 -4 -3 console log    range -2  -5      -2 -3 -4

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Pythonic styled way   range    start  end  step    gt    let arr      for let n start n lt end n   step  1   arr push n  return arr

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This may not be the best way  But if you are looking to get a range of numbers in a single line of code  For example 10 - 50  Array 40  fill undefined  map  n  i    gt  i   10    Where 40 is  end - start  and 10 is the start  This should return  10  11       50

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Handy function to do the trick  run the code snippet below   x000D   x000D  function range start  end  step  offset    x000D     x000D    var len    Math abs end - start      offset    0    2      step    1    1  x000D    var direction   start  lt  end   1   -1  x000D    var startingPoint   start -  direction    offset    0    x000D    var stepSize   direction    step    1   x000D     x000D    return Array len  fill 0  map function    index    x000D      return startingPoint    stepSize   index   x000D        x000D     x000D    x000D   x000D  console log  range 1  5   gt      range 1  5    x000D  console log  range 5  1   gt      range 5  1    x000D  console log  range 5  5   gt      range 5  5    x000D  console log  range -5  5   gt      range -5  5    x000D  console log  range -10  5  5   gt      range -10  5  5    x000D  console log  range 1  5  1  2   gt      range 1  5  1  2    x000D   x000D   x000D    here is how to use it  range  Start  End  Step 1  Offset 0     inclusive - forward   range 5 10        5  6  7  8  9  10  inclusive - backward  range 10 5        10  9  8  7  6  5  step - backward  range 10 2 2        10  8  6  4  2  exclusive - forward   range 5 10 0 -1        6  7  8  9   not 5 10 themselves offset - expand     range 5 10 0 1        4  5  6  7  8  9  10  11  offset - shrink     range 5 10 0 -2        7  8  step - expand    range 10 0 2 2        12  10  8  6  4  2  0  -2    hope you find it useful     And here is how it works   Basically I m first calculating the length of the resulting array and create a zero filled array to that length  then fill it with the needed values    step    1     And others like this means use the value of step and if it was not provided use 1 instead We start by calculating the length of the result array using   Math abs end - start      offset    0    2      step    1    1  to put it simpler  difference  offset in both direction step  After getting the length  then we create an empty array with initialized values using new Array length  fill 0   check here Now we have an array  0 0 0     to the length we want  We map over it and return a new array with the values we need by using Array map function       var direction   start  lt  end   1   0  Obviously if start is not smaller than the end we need to move backward  I mean going from 0 to 5 or vice versa On every iteration  startingPoint   stepSize   index will gives us the value we need

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Array from Array  m - n   1     v  i    gt  n   i      m  gt  n and both of them are integers

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In order to work where either given number could be larger I wrote this   function getRange start  end      return Array from       length  1   Math abs end - start           i    gt  end  gt  start   start   i   start - i

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Not implemented yet  Using the new Number range proposal  stage 1       Number range 1  10       gt   1  2  3  4  5  6  7  8  9  10

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just made something like this as an exercise in Eloquent JavaScript  function range start  end  step      var ar         if  start  lt  end        if  arguments length    2  step   1      for  var i   start  i  lt   end  i    step          ar push i               else       if  arguments length    2  step   -1      for  var i   start  i  gt   end  i    step          ar push i               return ar

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Per my understanding    JS  runtime environment doesn t support Tail Call Optimization  Writing any recursive function to generate a large range is going to bring you here  Creating arrays for looping might not be the best thing to do if we are going to work with large numbers  Writing large loops causes the event queue to slow down     function range start  end  step   1      const  range    start   gt  f   gt        if   start  lt  end          f  start         setTimeout      gt   range  start   step  f   0                return       map   range start           range 0  50000  map console log      This function doesn t raise the aforementioned concerns

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My take using conditional ternary operators in the for loop  no argument testing  though    function range start end step      var resar          for  var i start  step lt 0   i gt  end i lt  end   i     step    undefined   1 step           resar push i              return resar

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I just created this polyfill on the Array via Object defineProperty to make a range for integers or strings  The Object defineProperty is a safer way to create polyfills   The safer polyfill  if   Array range      Object defineProperty Array   range         value  function  from  to  step          if  typeof from      number   amp  amp  typeof from      string             throw new TypeError  The first parameter should be a number or a character                  if  typeof to      number   amp  amp  typeof to      string             throw new TypeError  The second parameter should be a number or a character                  var A            if  typeof from      number             A 0    from         step   step    1         while  from   step  lt   to              A A length    from    step                   else           var s    abcdefghijklmnopqrstuvwxyz          if  from     from toUpperCase                to   to toUpperCase             s   s toUpperCase                     s   s substring s indexOf from   s indexOf to    1          A   s split                   return A              else     var errorMessage    DANGER ALERT  Array range has already been defined on this browser      errorMessage     This may lead to unwanted results when Array range   is executed     console log errorMessage      Examples  Array range 1  3      Return   1  2  3    Array range 1  3  0 5      Return   1  1 5  2  2 5  3    Array range  a    c       Return    a    b    c     Array range  A    C       Return    A    B    C     Array range null  Array range undefined  Array range NaN  Array range true  Array range     Array range     Array range 1  null      Return  Uncaught TypeError  The X parameter should be a number or a character

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more range  using a generator function   function range s  e  str        create generator that handles numbers  amp  strings    function  gen s  e  str       while s  lt   e         yield   str    s   str s        s               if  typeof s      string   amp  amp   str      str    abcdefghijklmnopqrstuvwxyz    const from     str    s   str indexOf s    const to     str    e   str indexOf e       use the generator and return    return     gen from  to  str         usage     console log range  l    w        gt     l    m    n    o    p    q    r    s    t    u    v    w     console log range 7  12       gt    7  8  9  10  11  12       first  o  to first  t  of passed in string  console log range  o    t    ssshhhooooouuut             gt     o    o    o    o    o    u    u    u    t        only lowercase args allowed here  but     console log range  m    v   map v  gt v toUpperCase         gt     M    N    O    P    Q    R    S    T    U    V          gt  and decreasing range     console log range  m    v   map v  gt v toUpperCase    reverse          gt      and with a step console log range  m    v              map v  gt v toUpperCase               reverse              reduce  acc  c  i    gt   i   2    acc concat c    acc               etc  etc    Hope this is useful

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https   stackoverflow com a 49577331 8784402 With Delta Step smallest and one-liner     Array N   map     i    gt  from   i   step    Examples and other alternatives     Array 10   map     i    gt  4   i   2       gt   4  6  8  10  12  14  16  18  20  22   Array from Array 10   map     i    gt  4   i   2       gt   4  6  8  10  12  14  16  18  20  22   Array from Array 10  keys    map i   gt  4   i   2       gt   4  6  8  10  12  14  16  18  20  22       Array 10  keys    map i   gt  4   i   -2       gt   4  2  0  -2  -4  -6  -8  -10  -12  -14   Array 10  fill 0  map     i    gt  4   i   2       gt   4  6  8  10  12  14  16  18  20  22   Array 10  fill   map     i    gt  4   i   -2       gt   4  2  0  -2  -4  -6  -8  -10  -12  -14   Range Function const range    from  to  step    gt        Array Math floor  to - from    step    1   map     i    gt  from   i   step    range 0  9  2       gt   0  2  4  6  8      can also assign range function as static method in Array class  but not recommended   Array range    from  to  step    gt        Array Math floor  to - from    step    1   map     i    gt  from   i   step    Array range 2  10  2       gt   2  4  6  8  10   Array range 0  10  1       gt   0  1  2  3  4  5  6  7  8  9  10   Array range 2  10  -1       gt      Array range 3  0  -1       gt   3  2  1  0   As Iterators class Range     constructor total   0  step   1  from   0        this Symbol iterator    function             for  let i   0  i  lt  total  yield from   i     step                       new Range 5       Five Elements     gt    0  1  2  3  4      new Range 5  2       Five Elements With Step 2     gt    0  2  4  6  8      new Range 5  -2  10       Five Elements With Step -2 From 10     gt  10  8  6  4  2      new Range 5  -2  -10       Five Elements With Step -2 From -10     gt    -10  -12  -14  -16  -18      Also works with for  of loop for  i of new Range 5  -2  10   console log i      10 8 6 4 2  As Generators Only const Range   function   total   0  step   1  from   0      for  let i   0  i  lt  total  yield from   i     step         Array from Range 5  -2  -10        gt    -10  -12  -14  -16  -18       Range 5  -2  -10       Five Elements With Step -2 From -10     gt    -10  -12  -14  -16  -18      Also works with for  of loop for  i of Range 5  -2  10   console log i      10 8 6 4 2     Lazy loaded way const number0toInf   Range Infinity   number0toInf next   value      gt  0 number0toInf next   value      gt  1         From-To with steps delta using iterators class Range2     constructor to   0  step   1  from   0        this Symbol iterator    function             let i   0          length   Math floor  to - from    step    1        while  i  lt  length  yield from   i     step                   new Range2 5       First 5 Whole Numbers     gt   0  1  2  3  4  5       new Range2 5  2       From 0 to 5 with step 2     gt    0  2  4       new Range2 5  -2  10       From 10 to 5 with step -2     gt    10  8  6   using Generators const Range2   function   to   0  step   1  from   0      let i   0      length   Math floor  to - from    step    1    while  i  lt  length  yield from   i     step          Range2 5  -2  10       From 10 to 5 with step -2     gt    10  8  6   let even4to10   Range2 10  2  4   even4to10 next   value      gt  4 even4to10 next   value      gt  6 even4to10 next   value      gt  8 even4to10 next   value      gt  10 even4to10 next   value      gt  undefined  For Typescript class  Array lt T gt  extends Array lt T gt      static range from  number  to  number  step  number   number         return Array from Array Math floor  to - from    step    1   map         v  k    gt  from   k   step               Array range 0  9  1    https   stackoverflow com a 64599169 8784402 Generate Character List with one-liner  x000D   x000D  const charList    a z d 1   gt  a a charCodeAt   z z charCodeAt       Array Math floor  z-a  d  1   map    i   gt String fromCharCode a i d      console log  from A to G   charList  A    G     console log  from A to Z with step delta of 2   charList  A    Z   2    console log  reverse order from Z to P   charList  Z    P   -1    console log  from 0 to 5   charList  0    5   1    console log  from 9 to 5   charList  9    5   -1    console log  from 0 to 8 with step 2   charList  0    8   2    console log  from a to     charList  a          console log  Hindi characters from   to     charList             console log  Russian characters from   to     charList             x000D   x000D   x000D   For TypeScript const charList    p  string  q  string  d   1    gt      const a   p charCodeAt 0       z   q charCodeAt 0     return     Array Math floor  z - a    d    1   map     i    gt      String fromCharCode a   i   d

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A range with a defined hard int has a ton of answers  but what if you don t know that step and you want a number of steps in-between instead   I wrote this code to do that  It s pretty self-explanatory    const stepScale    min  max  numberOfSteps    gt      const  numberOfSteps   numberOfSteps - 1   const scaleBy    max - min     numberOfSteps    const arr        for  let i   0  i  lt    numberOfSteps  i    1        arr push min   scaleBy   i        return arr    export default stepScale   stepScale 5  10  4      5  6 666666666666667  8 333333333333334  10    For npm at https   npm im  universalstandard step-scale

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This is what I use for numbers ranges   const rangeFrom0   end   gt      Array end   map     index    gt  index     or  const rangeExcEnd    start  step  end    gt      Array end - start   1       map     index    gt  index   start      filter x   gt  x   step     start   step

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d3 also has a built-in range function   See https   github com mbostock d3 wiki Arrays d3 range      d3 range  start   stop   step        Generates an array containing an arithmetic progression  similar to the Python built-in range  This method is often used to iterate over a sequence of numeric or integer values  such as the indexes into an array  Unlike the Python version  the arguments are not required to be integers  though the results are more predictable if they are due to floating point precision  If step is omitted  it defaults to 1     Example   d3 range 10     returns  0  1  2  3  4  5  6  7  8  9

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function check         var correct true       for var i 0  i lt arguments length  i          if typeof arguments i      number         correct false       return correct          ------------------------------------------   function range start step end      var correct check start step end      if correct  amp  amp   step  amp  amp  end   0       for var i start  i lt  end  i  step     document write i            else document write  Not Correct Data

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This one works also in reverse   const range     a   b     gt  Array from  new Array  b  gt  a   b - a   a - b      x  i     gt  b  gt  a   i   a   a - i     range  -3  2         -3  -2  -1  0  1   range  1  -4         1  0  -1  -2  -3

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I found a JS range function equivalent to the one in PHP  and works amazingly great here  Works forward  amp  backward  and works with integers  floats and alphabets   function range low  high  step          discuss at  http   phpjs org functions range       original by  Waldo Malqui Silva        example 1  range   0  12           returns 1   0  1  2  3  4  5  6  7  8  9  10  11  12         example 2  range  0  100  10           returns 2   0  10  20  30  40  50  60  70  80  90  100         example 3  range   a    i            returns 3    a    b    c    d    e    f    g    h    i          example 4  range   c    a            returns 4    c    b    a      var matrix         var inival  endval  plus    var walker   step    1    var chars   false     if   isNaN low   amp  amp   isNaN high         inival   low      endval   high      else if  isNaN low   amp  amp  isNaN high         chars   true      inival   low charCodeAt 0       endval   high charCodeAt 0       else       inival    isNaN low    0   low       endval    isNaN high    0   high          plus     inival  gt  endval    false   true     if  plus        while  inival  lt   endval          matrix push   chars    String fromCharCode inival    inival          inival    walker            else       while  inival  gt   endval          matrix push   chars    String fromCharCode inival    inival          inival -  walker               return matrix      And here is the minified version   function range h c b  var i    var d f e var a b  1 var g false if  isNaN h  amp  amp  isNaN c   d h f c else if isNaN h  amp  amp isNaN c   g true d h charCodeAt 0  f c charCodeAt 0  else d  isNaN h  0 h  f  isNaN c  0 c   e   d gt f  false true  if e  while d lt  f  i push   g  String fromCharCode d  d   d  a  else while d gt  f  i push   g  String fromCharCode d  d   d- a  return i

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If we input something like  4  2   we   ll get  2  3  4  as output  we can work with that   function createRange array      var range         var highest   array reduce function a  b        return Math max a  b           var lowest   array reduce function a  b        return Math min a  b           for  var i   lowest  i  lt   highest  i          range push i         return range

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None of the examples had tests  implementation for step with an option to produce decreasing values   export function range start   0  end   0  step   1        if  start     end    step     0            return                const diff   Math abs end - start       const length   Math ceil diff   step        return start  gt  end           Array from  length    value  key    gt  start - key   step            Array from  length    value  key    gt  start   key   step        Tests   import range from    range   describe  Range        gt        it  default        gt            expect range    toMatchObject                  it  same values        gt            expect range 1 1   toMatchObject                  it  step 0        gt            expect range 0 1 0   toMatchObject                  describe  step 1        gt            it  normal        gt                expect range 6 12   toMatchObject  6  7  8  9  10  11                        it  reversed        gt                expect range 12 6   toMatchObject  12  11  10  9  8  7                           describe  step 5        gt             it  start 0 end 60        gt                expect range 0  60  5   toMatchObject  0  5  10  15  20  25  30  35  40  45  50  55                        it  reversed start 60 end -1        gt                expect range 55  -1  5   toMatchObject  55  50  45  40  35  30  25  20  15  10  5  0

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Simple range function  function range start  stop  step        var a    start   b   start      while  b  lt  stop            a push b    step    1             return a      To incorporate the BigInt data type some check can be included   ensuring that all variables are same typeof start  function range start  stop  step        var a    start   b   start      if  typeof start     bigint             stop   BigInt stop          step   step  BigInt step   1n        else         step   step    1      while  b  lt  stop            a push b    step             return a      To remove values higher than defined by stop e g  range 0 5 2  will include 6  which shouldn t be  function range start  stop  step        var a    start   b   start      while  b  lt  stop            a push b    step    1             return  b  gt  stop    a slice 0 -1    a

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The standard Javascript doesn t have a built-in function to generate ranges   Several javascript frameworks add support for such features  or as others have pointed out you can always roll your own   If you d like to double-check  the definitive resource is the ECMA-262 Standard

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range start end step   With ES6 Iterators  You only ask for an upper and lower bounds  Here we create one with a step too   You can easily create range   generator function which can function as an iterator  This means you don t have to pre-generate the entire array   function   range   start  end  step   1       let state   start    while   state  lt  end         yield state      state    step        return       Now you may want to create something that pre-generates the array from the  iterator and returns a list  This is useful for functions that accept an array  For this we can use Array from    const generate array    start end step    gt    Array from  range start end step       Now you can generate a static array easily   const array1   generate array 1 10 2   const array1   generate array 1 7     But when something desires an iterator  or gives you the option to use an iterator  you can easily create one too   for   const i of range 1  Number MAX SAFE INTEGER  7        console log i      Special Notes   If you use Ramda  they have their own R range as does Lodash

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Here s my 2 cents   function range start  count      return Array apply 0  Array count        map  element  index    gt  index   start

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One liner that can work in either direction  const range    a b   gt Array Math abs a-b  1  fill a  map  v i   gt v i  a gt b -1 1     See in action   x000D   x000D  const range    a b    gt  Array Math abs a-b  1  fill a  map  v i   gt v i  a gt b -1 1     console log range 1 4    console log range 4 1    x000D   x000D   x000D

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There s an npm module bereich for that   bereich  is the German word for  range    It makes use of modern JavaScript s iterators  so you can use it in various ways  such as   console log    bereich 1  10         gt  1  2  3  4  5  6  7  8  9  10  const numbers   Array from bereich 1  10         gt    1  2  3  4  5  6  7  8  9  10    for  const number of bereich 1  10                  It also supports descending ranges  by simply exchanging min and max   and it also supports steps other than 1   Disclaimer  I am the author of this module  so please take my answer with a grain of salt

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For letters  he s a simple vanilla JS solution I came up with to generate letter ranges   It s intended to generate arrays of upper- or lowercase letters  only    x000D   x000D  function range first  last    x000D      var r       x000D          i   first charCodeAt 0   x000D       x000D      while i  lt   last charCodeAt 0     x000D          r push String fromCharCode i      x000D        x000D       x000D      return r  x000D    x000D   x000D  console dir range  a    f     x000D  console dir range  G    Z     x000D   x000D   x000D

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As far as generating a numeric array for a given range  I use this     function range start  stop        var array            var length   stop - start        for  var i   0  i  lt   length  i               array i    start          start               return array     console log range 1  7         1 2 3 4 5 6 7  console log range 5  10        5 6 7 8 9 10  console log range -2  3        -2 -1 0 1 2 3    Obviously  it won t work for alphabetical arrays

[javascript] Does JavaScript have a method like "range()" to generate a range within the supplied bounds?

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