How can I create a two dimensional array in JavaScript

Question

I have been reading online and some places say it isn t possible  some say it is and then give an example and others refute the example  etc     How do I declare a 2 dimensional array in JavaScript   assuming it s possible   How would I access its members   myArray 0  1  or myArray 0 1

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Two dimensional arrays are created the same way single dimensional arrays are   And you access them like array 0  1    var arr    1  2   3  4   5    alert  arr 2  1      alerts  4

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I found that this code works for me   var map                mapWidth   50  mapHeight   50  fillEmptyMap map  mapWidth  mapHeight          function fillEmptyMap array  width  height        for  var x   0  x  lt  width  x              array x                for  var y   0  y  lt  height  y                   array x  y     0

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You could allocate an array of rows  where each row is an array of the same length  Or you could allocate a one-dimensional array with rows columns elements and define methods to map row column coordinates to element indices   Whichever implementation you pick  if you wrap it in an object you can define the accessor methods in a prototype to make the API easy to use

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I m not a fan of the ES6 solutions using  fill     Some may work but the extra hoops to avoid the copy-by-reference problems make them non-intuitive     My suggested ES6 approach is to fully leverage the spread operator for both outer and inner arrays   It s easier to reason about IMO       Array 3   map      gt      Array 4      If you need to set an initial value  then you chain on a  map   on the inner array creation       Array 3   map      gt      Array 4   map      gt  0     Lastly  a type-safe TypeScript util function   export const createMultiDimensionalArray    lt T gt     n  number    m  number    initialVal   T     T       gt      const matrix       Array n   map      gt      Array m       return initialVal     undefined       matrix       matrix map r   gt  r map      gt  initialVal         Examples using it   const a   createMultiDimensionalArray 1  2   a 1  2    3         Works  const b   createMultiDimensionalArray 2  3  false   b 1  2    true      Works b 1  2    3         Error  Type  3  is not assignable to type  boolean

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If all you want is a 4x4 matrix have a look at DOMMatrix  it is easy to use I can say   let m   new DOMMatrix        m m11  m m12  m m13  m m14       m m41  m m42  m m43  m m44   Initially brought for different reasons  it is not available on node js and only limited to 4x4   Also you can consider using an auto-vivification object instead arrays for JS  have a look at my answer here but brought here also for more convince   var tree        gt  new Proxy       get   target  name    gt  name in target   target name    target name    tree        var t   tree    t 0  2  3    4  console log t 0  2  3      It uses new JS and acts not correctly when you iterate through it so be careful with it   Also have a look at this if you need a flexible multi-dimension array generator

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To create a non-sparse  2D  array  x y  with all indices addressable and values set to null   let 2Darray   new Array x  fill null  map item   gt  new Array y  fill null       bonus  3D  Array  x y z   let 3Darray   new Array x  fill null  map item  gt  new Array y  fill null   map item  gt Array z  fill null      Variations and corrections on this have been mentioned in comments and at various points in response to this question but not as an actual answer so I am adding it here   It should be noted that  similar to most other answers  this has O x y  time complexity so it probably not suitable for very large arrays

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Creates n dimensional matrix array for Java Script  filling with initial default of value 0   function arr  arg  def   0         if  arg length  gt  2           return Array arg 0   fill   map     gt arr arg slice 1             else           return Array arg 0   fill   map     gt Array arg 1   fill def                      Simple Usage of 4 dimensions var s   arr  3 8 4 6       Use null default value with 2 dimensions var k   arr  5 6    null

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I ve made a modification of Matthew Crumley s answer for creating a multidimensional array function  I ve added the dimensions of the array to be passed as array variable and there will be another variable - value  which will be used to set the values of the elements of the last arrays in the multidimensional array          Function to create an n-dimensional array        param array dimensions      param any type value        return array array     function createArray dimensions  value           Create new array     var array   new Array dimensions 0     0       var i   dimensions 0           If dimensions array s length is bigger than 1        we start creating arrays in the array elements with recursions        to achieve multidimensional array     if  dimensions length  gt  1               Remove the first value from the array         var args   Array prototype slice call dimensions  1              For each index in the created array create a new array with recursion         while i--                array dimensions 0 -1 - i    createArray args  value                    If there is only one element left in the dimensions array        assign value to each of the new array s elements if value is set as param       else           if  typeof value      undefined                 while i--                    array dimensions 0 -1 - i    value                                     return array     createArray                         or new Array    createArray  2    empty            empty    empty    createArray  3  2   0              0  0                                      0  0                                      0  0

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You can also create a function to create a 2D array like this   var myTable        function createArray myLength        myTable   new Array myLength       var cols  rows      for  cols   0  cols  lt  myLength  cols              myTable cols    new Array myLength             You can call it by using the following  which will give you a 10x10 2D array   createArray 10     You also can create a 3D array using this method

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Row and Column sizes of an array known only at the run time then following method could be used for creating a dynamic 2d array   x000D   x000D      var num    123456       var row   3     Known at run time     var col   2     Known at run time     var i   0           var array2D             for var r   0  r  lt  row    r                array2D r                for var c   0  c  lt  col    c                        array2D r  c    num i                         console log array2D               1    2                 3    4                 5    6              console log array2D 2  1       6 x000D   x000D   x000D

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The easiest way   var arr         var arr1     00   01    var arr2     10   11    var arr3     20   21     arr push arr1   arr push arr2   arr push arr3    alert arr 0  1        01  alert arr 1  1        11  alert arr 2  0        20

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Performance  Today 2020 02 05 I perform tests on MacOs HighSierra 10 13 6 on Chrome v79 0  Safari v13 0 4 and Firefox v72 0  for chosen solutions   Conclusions for non-initialised 2d array   esoteric solution    arr  i j    N  is fastest for big and small arrays and it looks like it is good choice for big sparse arrays solutions based on for-   while  A G  are fast and they are good choice for small arrays  solutions for-    B C  are fast and they are good choice for big arrays solutions based on Array  map from fill  I J K L M  are quite slow for small arrays  and quite fast for big arrays surprinsingly for-Array n   B C  is much slower on safari than for-    A  surprinsingly for-    A  for big array is slow on all browsers solutions K is slow for small arrays for all browsers solutions A E G are slow for big arrays for all browsers solution M is slowest for all arrays on all browsers     Conclusions for initialised 2d array   solutions based on for while  A B C D E G  are fastest quite fast for small arrays on all browsers solutions based on for  A B C E  are fastest quite fast for big arrays on all browsers solutions based on Array  map from fill  I J K L M  are medium fast or slow for small arrays on all browsers solutions F G H I J K L for big arrays are medium or fast on chrome and safari but slowest on firefox  esoteric solution    arr  i j    N  is slowest for small and big arrays on all browsers     Details  Test for solutions which not fill  initialise  output array  We test speed of solutions for   small arrays  12 elements  - you can perform tests on your machine HERE big arrays  1 million elements  arrays - you can perform tests on your machine HERE    x000D   x000D  function A r    x000D    var arr       x000D    for  var i   0  i  lt  r  i    arr i        x000D    return arr  x000D    x000D   x000D  function B r  c    x000D    var arr   new Array r   x000D    for  var i   0  i  lt  arr length  i    arr i    new Array c   x000D    return arr  x000D    x000D   x000D  function C r  c    x000D    var arr   Array r   x000D    for  var i   0  i  lt  arr length  i    arr i    Array c   x000D    return arr  x000D    x000D   x000D  function D r  c    x000D       strange  but works x000D    var arr       x000D    for  var i   0  i  lt  r  i      x000D      arr push      x000D      arr i  push Array c    x000D      x000D    return arr  x000D    x000D   x000D  function E r  c    x000D    let array         x000D    for  var x   0  x  lt  c  x      x000D      array x        x000D      for  var y   0  y  lt  r  y    array x  y     0   x000D      x000D    return array  x000D    x000D   x000D  function F r  c    x000D    var makeArray   function dims  arr    x000D      if  dims 1      undefined    x000D        return Array dims 0    x000D        x000D   x000D      arr   Array dims 0    x000D   x000D      for  var i   0  i  lt  dims 0   i      x000D        arr i    Array dims 1    x000D        arr i    makeArray dims slice 1   arr i    x000D        x000D   x000D      return arr  x000D      x000D    return makeArray  r  c    x000D    x000D   x000D  function G r    x000D    var a       x000D    while  a push      lt  r   x000D    return a  x000D    x000D   x000D  function H r c    x000D    function createArray length    x000D      var arr   new Array length    0   x000D          i   length  x000D   x000D      if  arguments length  gt  1    x000D          var args   Array prototype slice call arguments  1   x000D          while i--  arr length-1 - i    createArray apply this  args   x000D        x000D   x000D      return arr  x000D      x000D    return createArray r c   x000D    x000D   x000D  function I r  c    x000D    return     Array r   map x   gt  Array c    x000D    x000D   x000D  function J r  c    x000D    return Array r  fill 0  map      gt  Array c    x000D    x000D   x000D  function K r  c    x000D    return Array from Array r        gt  Array c    x000D    x000D   x000D  function L r  c    x000D    return Array from  length  r   map e   gt  Array c    x000D    x000D   x000D  function M r  c    x000D    return Array from  length  r        gt  Array from  length  c        gt        x000D    x000D   x000D  function N r  c    x000D    return    x000D    x000D   x000D   x000D   x000D     ----------------------------------------------- x000D     SHOW x000D     ----------------------------------------------- x000D   x000D  log    t  f    gt    x000D    let A   f 3  4      create array with 3 rows and 4 columns x000D    A 1  2    6    2-nd row 3nd column set to 6 x000D    console log    t  1  2     A 1  2    full    JSON stringify A  replace  null g  x       x000D    x000D   x000D  log2    t  f    gt    x000D    let A   f 3  4      create array with 3 rows and 4 columns x000D    A  1 2     6    2-nd row 3nd column set to 6 x000D    console log    t  1  2     A  1 2     full    JSON stringify A  replace  null g  x       x000D    x000D   x000D  log  A   A   x000D  log  B   B   x000D  log  C   C   x000D  log  D   D   x000D  log  E   E   x000D  log  F   F   x000D  log  G   G   x000D  log  H   H   x000D  log  I   I   x000D  log  J   J   x000D  log  K   K   x000D  log  L   L   x000D  log  M   M   x000D  log2  N   N   x000D  This is presentation of solutions - not benchmark x000D   x000D   x000D    Test for solutions which fill  initialise  output array  We test speed of solutions for   small arrays  12 elements  - you can perform tests on your machine HERE big arrays  1 million elements  arrays - you can perform tests on your machine HERE    x000D   x000D  function A r  c  def    x000D    var arr       x000D    for  var i   0  i  lt  r  i    arr i    Array c  fill def   x000D    return arr  x000D    x000D   x000D  function B r  c  def    x000D    var arr   new Array r   x000D    for  var i   0  i  lt  arr length  i    arr i    new Array c  fill def   x000D    return arr  x000D    x000D   x000D  function C r  c  def    x000D    var arr   Array r   x000D    for  var i   0  i  lt  arr length  i    arr i    Array c  fill def   x000D    return arr  x000D    x000D   x000D  function D r  c  def    x000D       strange  but works x000D    var arr       x000D    for  var i   0  i  lt  r  i      x000D      arr push      x000D      arr i  push Array c    x000D      x000D    for  var i   0  i  lt  r  i    for  var j   0  j  lt  c  j    arr i  j  def x000D    return arr  x000D    x000D   x000D  function E r  c  def    x000D    let array         x000D    for  var x   0  x  lt  c  x      x000D      array x        x000D      for  var y   0  y  lt  r  y    array x  y    def  x000D      x000D    return array  x000D    x000D   x000D  function F r  c  def    x000D    var makeArray   function dims  arr    x000D      if  dims 1      undefined    x000D        return Array dims 0   fill def   x000D        x000D   x000D      arr   Array dims 0    x000D   x000D      for  var i   0  i  lt  dims 0   i      x000D        arr i    Array dims 1    x000D        arr i    makeArray dims slice 1   arr i    x000D        x000D   x000D      return arr  x000D      x000D    return makeArray  r  c    x000D    x000D   x000D  function G r  c  def    x000D    var a       x000D    while  a push Array c  fill def    lt  r   x000D    return a  x000D    x000D   x000D  function H r c  def    x000D    function createArray length    x000D      var arr   new Array length    0   x000D          i   length  x000D   x000D      if  arguments length  gt  1    x000D          var args   Array prototype slice call arguments  1   x000D          while i--  arr length-1 - i    createArray apply this  args  fill def   x000D        x000D   x000D      return arr  x000D      x000D    return createArray r c   x000D    x000D   x000D  function I r  c  def    x000D    return     Array r   map x   gt  Array c  fill def    x000D    x000D   x000D  function J r  c  def    x000D    return Array r  fill 0  map      gt  Array c  fill def    x000D    x000D   x000D  function K r  c  def    x000D    return Array from Array r        gt  Array c  fill def    x000D    x000D   x000D  function L r  c  def    x000D    return Array from  length  r   map e   gt  Array c  fill def    x000D    x000D   x000D  function M r  c  def    x000D    return Array from  length  r        gt  Array from  length  c        gt  def    x000D    x000D   x000D  function N r  c  def    x000D    let arr     x000D    for  var i   0  i  lt  r  i    for  var j   0  j  lt  c  j    arr  i j   def  x000D    return arr  x000D    x000D   x000D   x000D   x000D     ----------------------------------------------- x000D     SHOW x000D     ----------------------------------------------- x000D   x000D  log    t  f    gt    x000D    let A   f 1000 1000 7      create array with 1000 rows and 1000 columns   x000D                               each array cell initilised by 7 x000D    A 800  900    5            800nd row and 901nd column set to 5 x000D    console log    t  1  2     A 1  2      t  800  901     A 800  900      x000D    x000D   x000D  log2    t  f    gt    x000D    let A   f 1000 1000 7      create array with 1000 rows and 1000 columns   x000D                               each array cell initilised by 7 x000D    A  800 900     5               800nd row 900nd column set to 5 x000D    console log    t  1  2     A  1 2       t  800  900     A  800 900       x000D    x000D   x000D  log  A   A   x000D  log  B   B   x000D  log  C   C   x000D  log  D   D   x000D  log  E   E   x000D  log  F   F   x000D  log  G   G   x000D  log  H   H   x000D  log  I   I   x000D  log  J   J   x000D  log  K   K   x000D  log  L   L   x000D  log  M   M   x000D  log2  N   N   x000D  This is presentation of solutions - not benchmark x000D   x000D   x000D

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The sanest answer seems to be   x000D   x000D  var nrows      Math random     10   x000D  var ncols      Math random     10   x000D  console log  rows   nrows     x000D  console log  cols   ncols     x000D  var matrix   new Array nrows  fill 0  map row   gt  new Array ncols  fill 0    x000D  console log matrix   x000D   x000D   x000D      Note we can t directly fill with the rows since fill uses shallow copy constructor  therefore all rows would share the same memory   here is example which demonstrates how each row would be shared  taken from other answers       DON T do this  each row in arr  is shared var arr   Array 2  fill Array 4    arr 0  0     foo      also modifies arr 1  0  console info arr

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Here s a quick way I ve found to make a two dimensional array   function createArray x  y        return Array apply null  Array x   map e   gt  Array y        You can easily turn this function into an ES5 function as well   function createArray x  y        return Array apply null  Array x   map function e            return Array y               Why this works  the new Array n  constructor creates an object with a prototype of Array prototype and then assigns the object s length  resulting in an unpopulated array  Due to its lack of actual members we can t run the Array prototype map function on it   However  when you provide more than one argument to the constructor  such as when you do Array 1  2  3  4   the constructor will use the arguments object to instantiate and populate an Array object correctly   For this reason  we can use Array apply null  Array x    because the apply function will spread the arguments into the constructor  For clarification  doing Array apply null  Array 3   is equivalent to doing Array null  null  null    Now that we ve created an actual populated array  all we need to do is call map and create the second layer  y

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I m not sure if anyone has answered this but I found this worked for me pretty well -   var array               eg    var a     1 2   3 4     For a 2 dimensional array  for instance

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Two-liner   var a        while a push      lt  10     It will generate an array a of the length 10  filled with arrays   Push adds an element to an array and returns the new length

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Below one  creates a 5x5 matrix and fill them with null   x000D   x000D  var md       x000D  for var i 0  i lt 5  i      x000D      md push new Array 5  fill null    x000D    x000D   x000D  console log md   x000D   x000D   x000D

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To create an 4x6 array  simply do this const x       new Array 6   map elem   gt  new Array 4    It s usually a good practice to start with an empty array  rather than filling w random values   You normally declare array as const x      in 1D  so better to start w empty in 2D

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My approach is very similar to  Bineesh answer but with a more general approach   You can declare the double array as follows   var myDoubleArray           And the storing and accessing the contents in the following manner   var testArray1    9 8  var testArray2    3 5 7 9 10  var testArray3     test  123  var index   0   myDoubleArray index      testArray1  myDoubleArray index      testArray2  myDoubleArray index      testArray3   console log myDoubleArray 0  myDoubleArray 1  3   myDoubleArray 2   test        This will print the expected output    9  8   9 123

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nodejs   lodash version    var     require  lodash    var result     chunk   a    b    c    d    e    f    2   console log result   console log result 2  0      The output        a    b        c    d        e    f      e

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Recursive function to create a multi-dimensional array   var makeArray   function  dims  arr                  if  dims 1      undefined            return new Array dims 0               arr   new Array dims 0         for  var i 0  i lt dims 0   i              arr i    new Array dims 1            arr i    makeArray dims slice 1   arr i               return arr      Build a 2x3x4x2 4D-Array   var array   makeArray  2  3  4  2

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ES6   ES2015  can do this in even simpler way    Creating 3 x 2 Array filled with true      Array 3   map item   gt  Array 2  fill true

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The easiest way   var myArray

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Javascript only has 1-dimensional arrays  but you can build arrays of arrays  as others pointed out   The following function can be used to construct a 2-d array of fixed dimensions   function Create2DArray rows      var arr          for  var i 0 i lt rows i           arr i               return arr      The number of columns is not really important  because it is not required to specify the size of an array before using it   Then you can just call   var arr   Create2DArray 100    arr 50  2    5  arr 70  5    7454

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Javascript does not support two dimensional arrays  instead we store an array inside another array and fetch the data from that array depending on what position of that array you want to access  Remember array numeration starts at ZERO   Code Example      Two dimensional array that s 5 x 5          C0 C1 C2 C3 C4      R0 1  1  1  1  1       R1 1  1  1  1  1       R2 1  1  1  1  1       R3 1  1  1  1  1       R4 1  1  1  1  1       var row0    1 1 1 1 1       row1    1 1 1 1 1       row2    1 1 1 1 1       row3    1 1 1 1 1       row4    1 1 1 1 1    var table    row0 row1 row2 row3 row4   console log table 0  0       Get the first item in the array

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What happens if the size of array is unknown  Or array should be dynamically created and populated  Alternative solution which worked for me is to use class with static 2d array variable which in case of non-existence of index in array will initiate it   function  a x y val          return depending on parameters     switch arguments length           case 0  return  a a          case 1  return  a a x           case 2  return  a a x  y                 declare array if wasn t declared yet     if typeof  a a x      undefined            a a x              a a x  y    val       declare static empty variable  a a         The syntax will be    a 1 1 2      populates  1  1  with value 2  a 1 1        2 or alternative syntax  a a 1  1   a 1           undefined    1  2   a a           undefined    1  Array 2    a a length

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If you are after 2D array for google charts  the best way to do it is   var finalData          key  value     2013-8-5   13 5     2013-7-29  19 7        referring to  Not a valid 2d array google chart

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I found below is the simplest way   x000D   x000D  var array1            array1 0  100    5        alert array1 0  100    alert array1 length   alert array1 0  length   x000D   x000D   x000D

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A simplified example   var blocks        blocks 0         blocks 0  0    7

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Array from  length  rows   map e   gt  new Array columns

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How to create an empty two dimensional array  one-line   Array from Array 2        gt  new Array 4     2 and 4 being first and second dimensions respectively   We are making use of Array from  which can take an array-like param and an optional mapping for each of the elements      Array from arrayLike   mapFn   thisArg       x000D   x000D  var arr   Array from Array 2        gt  new Array 4    x000D  arr 0  0     foo   x000D  console info arr   x000D   x000D   x000D    The same trick can be used to Create a JavaScript array containing 1   N    Alternatively  but more inefficient 12  with n   10 000   Array 2  fill null  map      gt  Array 4     The performance decrease comes with the fact that we have to have the first dimension values initialized to run  map  Remember that  Array will not allocate the positions until you order it to through  fill or direct value assignment    x000D   x000D  var arr   Array 2  fill null  map      gt  Array 4    x000D  arr 0  0     foo   x000D  console info arr   x000D   x000D   x000D      Follow up  Here s a method that appears correct  but has issues    Array 2  fill Array 4       BAD  Rows are copied by reference   While it does return the apparently desired two dimensional array       lt 4 empty items gt        lt 4 empty items gt        there a catch  first dimension arrays have been copied by reference  That means a arr 0  0     foo  would actually change two rows instead of one    x000D   x000D  var arr   Array 2  fill Array 4    x000D  arr 0  0     foo   x000D  console info arr   x000D  console info arr 0  0   arr 1  0    x000D   x000D   x000D

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var items             January 01   42 5           February 01    44 3           March 01    28 7           April 01    44 3           May 01    22 9           June 01    54 4           July 01    69 3           August 01    19 1           September 01    82 5           October 01    53 2           November 01    75 9           December 01    58 7            alert items 1  0       February 01   alert items 5  1       54 4

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Few people show the use of push  To bring something new  I will show you how to initialize the matrix with some value  example  0 or an empty string     Reminding that if you have a 10 elements array  in javascript the last index will be 9   function matrix  rows  cols  defaultValue      var arr             Creates all lines    for var i 0  i  lt  rows  i               Creates an empty line       arr push                Adds cols to the empty line        arr i  push  new Array cols           for var j 0  j  lt  cols  j                Initializes          arr i  j    defaultValue               return arr      usage examples    x   matrix  2   3         2 lines  3 cols filled with empty string y   matrix  10  5  0     10 lines  5 cols filled with 0

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You simply make each item within the array an array    x000D   x000D  var x   new Array 10   x000D   x000D  for  var i   0  i  lt  x length  i      x000D    x i    new Array 3   x000D    x000D   x000D  console log x   x000D   x000D   x000D

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This is what i achieved     x000D   x000D  var appVar         x000D  appVar 0  4     bineesh   x000D  appVar 0  5     kumar   x000D  console log appVar 0  4    appVar 0  5    x000D  console log appVar   x000D   x000D   x000D    This spelled me bineeshkumar

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One liner to create a m n 2 dimensional array filled with 0   new Array m  fill new Array n  fill 0

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x000D   x000D  var playList     x000D      I Did It My Way    Frank Sinatra    x000D      Respect    Aretha Franklin    x000D      Imagine    John Lennon    x000D      Born to Run    Bruce Springsteen    x000D      Louie Louie    The Kingsmen    x000D      Maybellene    Chuck Berry   x000D     x000D   x000D  function print message    x000D    document write message   x000D    x000D   x000D  function printSongs  songs     x000D    var listHTML  x000D    listHTML     lt ol gt    x000D    for   var i   0  i  lt  songs length  i    1    x000D      listHTML      lt li gt     songs i  0      by     songs i  1      lt  li gt    x000D      x000D    listHTML      lt  ol gt    x000D    print listHTML   x000D    x000D   x000D  printSongs playList   x000D   x000D   x000D

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There is another solution  that does not force you to pre-define the size of the 2d array  and that is very concise    x000D   x000D  var table      x000D  table  1 2     3    Notice the double    and    x000D  console log table  1 2       - gt  3 x000D   x000D   x000D    This works because   1 2  is transformed into a string  that is used as a string key for the table object

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Array m  fill v  map      gt  Array n  fill v    You can create a 2 Dimensional array m x n with initial value m and n can be any numbers v can be any value string  number  undefined  One approach can be var a    m  n

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Use Array Comprehensions  In JavaScript 1 7 and higher you can use array comprehensions to create two dimensional arrays  You can also filter and or manipulate the entries while filling the array and don t have to use loops   var rows    1  2  3   var cols     a    b    c    d     var grid     for  r of rows    for  c of cols  r c                    grid                   1a   1b   1c   1d                  2a   2b   2c   2d                  3a   3b   3c   3d                   You can create any n x m array you want and fill it with a default value by calling  var default   0      your 2d array will be filled with this value var n dim   2  var m dim   7    var arr     for  n of Array n dim     for  m of Array m dim  default                  arr                  0  0  0  0  0  0  0                0  0  0  0  0  0  0                   More examples and documentation can be found here   Please note that this is not a standard feature yet

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To create a 2D array in javaScript we can create an Array first and then add Arrays as it s elements  This method will return a 2D array with the given number of rows and columns        function Create2DArray rows columns       var x   new Array rows      for  var i   0  i  lt  rows  i             x i    new Array columns           return x      to create an Array use this method as below   var array   Create2DArray 10 20

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For one liner lovers Array from       creates 8x8 array filed with  0      const arr2d   Array from   length  8         gt  Array from   length  8         gt   0      Another one  from comment by dmitry romanov  use Array   fill       creates 8x8 array filed with  0      const arr2d   Array 8  fill 0  map      gt  Array 8  fill  0      Using ES6  spread operator   inspired  by InspiredJW answer          same as above just a little shorter const arr2d       Array 8   map      gt  Array 8  fill  0

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Similar to activa s answer  here s a function to create an n-dimensional array   function createArray length        var arr   new Array length    0           i   length       if  arguments length  gt  1            var args   Array prototype slice call arguments  1           while i--  arr length-1 - i    createArray apply this  args              return arr     createArray              or new Array    createArray 2         new Array 2   createArray 3  2       new Array 2                          new Array 2                          new Array 2

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An awesome repository here      api   masfufa js sample   masfufa html    Two Examples will be enough to understand this library     Example 1               1   2   3         MX    4   5   6       Dimensions  3 x 3             7   8   9               jsdk getAPI  my      var A  1  2  3  4  5  6  7  8  9     var MX myAPI getInstance  masfufa   data A dim  3x3       then     MX get 0  0      - gt  1  first  MX get 2  2      - gt 9  last    Example 2                1   9   3   4         MXB    4   5   6   2       Dimensions  2 x 4                     var B  1   9   3   4   4   5   6   2     var MXB myAPI getInstance  masfufa   data B dim  2x4       then     MXB get 0  0      - gt  1  first  MXB get 1  3      - gt  2  last  MXB get 1  2      - gt  6  before last

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var  field    function         var array           for var y   0  y    3  y      array y    new Array 5         return array            var item    field 2  4

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This is my implementation of Multi-Dimension Array   In this approach  I am creating a single dimension array  I have added a prototype function multi to Array object  Which can be used to create any dimension Array   I have also added a prototype function index to Array object  Which can be used to get index in linear Array from multi-dimension indexes   Creating a Array    Equivalent to arr I  J  K      in C var arr   new Array   multi I J K        Accessing array value at any index    Equivalent in C arr i  j  k   var vaue   arr arr index i j k      SNIPPET   x000D   x000D     x000D     Storing array as single dimension  x000D     and access using Array index i j k      x000D     x000D   x000D   x000D  Array prototype multi   function    x000D   this multi size   arguments  x000D   this multi len   1 x000D   for key in arguments  this multi len     arguments key   x000D   for var i 0 i lt this multi len i    this push 0   x000D   return this  x000D    x000D   x000D  Array prototype index   function    x000D     var  size   this multi len  x000D     var temp   1  x000D     var index   0  x000D     for key in arguments    x000D        temp  this multi size key   x000D        index   arguments key    size temp   x000D       x000D     return index  x000D    x000D   x000D     Now you can use the multi dimension array x000D     A 3x3 2D Matrix x000D   x000D  var arr2d   new Array   multi 3 3      A 2D Array x000D  arr2d arr2d index 1 1 1      5  x000D  console log arr2d arr2d index 1 1 1     x000D   x000D     A 3x3x3 3D Matrix x000D   x000D  var arr3d   new Array   multi 3 3 3      a 3D Array x000D  arr3d arr3d index 1 1 1      5  x000D  console log arr3d arr3d index 1 1 1     x000D   x000D     A 4x3x3 4D Matrix x000D  var arr4d   new Array   multi 4 3 3 3      a 4D Array x000D  arr4d arr4d index 4 0 0 1      5  x000D  console log arr4d arr4d index 4 0 0 1     x000D   x000D   x000D

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This is mentioned in a few of the comments  but using Array fill   will help construct a 2-d array   function create2dArr x y        var arr           for var i   0  i  lt  y  i              arr push Array x  fill 0              return arr       this will result in an array of length x  y times in the returned array

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x000D   x000D  var items     x000D     1  2   x000D     3  4   x000D     5  6  x000D     x000D  console log items 0  0       1 x000D  console log items 0  1       2 x000D  console log items 1  0       3 x000D  console log items 1  1       4 x000D  console log items   x000D   x000D   x000D

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I had to make a flexible array function to add  records  to it as i needed and to be able to update them and do whatever calculations e needed before i sent it to a database for further processing  Here s the code  hope it helps      function Add2List clmn1  clmn2  clmn3        aColumns push clmn1 clmn2 clmn3      Creates array with  record      aLine splice aPos  0 aColumns       Inserts new  record  at position aPos in main array     aColumns             Resets temporary array     aPos      Increments position not to overlap previous  records      Feel free to optimize and   or point out any bugs

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The reason some say that it isn t possible is because a two dimensional array is really just an array of arrays  The other comments here provide perfectly valid methods of creating two dimensional arrays in JavaScript  but the purest point of view would be that you have a one dimensional array of objects  each of those objects would be a one dimensional array consisting of two elements   So  that s the cause of the conflicting view points

[javascript] How can I create a two dimensional array in JavaScript?

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