Deep copying an array using jQuery

Question

Possible Duplicate    What is the most efficient way to clone a JavaScript object        I need to copy an  ordered  not associative  array of objects  I m using jQuery  I initially tried   jquery extend     myArray    but  naturally  this gives me back an object  where I need an array  really love jquery extend  by the way    So  what s the best way to copy an array

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how about complex types  when array contains objects    or any else  My variant   Object prototype copy   function        var v newObj           for v i in this          v newObj v i     typeof this v i   contains    array object       this v i  copy     this v i       return v newObj     Array prototype copy   function        var v newArr           this each function v i           v newArr push  typeof v i  contains    array object       v i copy     v i               return v newArr      It s not final version  just an idea   PS  method each and contains are prototypes also

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Since Array slice   does not do deep copying  it is not suitable for multidimensional arrays   var a    1    2    3    var b   a slice     b shift   shift       a is now       2    3     Note that although I ve used shift   shift   above  the point is just that b 0  0  contains a pointer to a 0  0  rather than a value     Likewise delete b 0  0   also causes  a 0  0  to be deleted and b 0  0  99 also changes the value of a 0  0  to 99   jQuery s extend method does perform a deep copy when a true value is passed as the initial argument   var a    1    2    3    var b     extend true      a    b shift   shift       a is still   1    2    3

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I ve come across this  deep object copy  function that I ve found handy for duplicating objects by value  It doesn t use jQuery  but it certainly is deep   http   www overset com 2007 07 11 javascript-recursive-object-copy-deep-object-copy-pass-by-value

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If you want to use pure JavaScript then try this    var arr   apple   ball   cat   dog     var narr       for var i 0 i lt arr length i          narr push arr i        alert narr     output  apple ball vat dog  narr push  elephant     alert arr      output  apple ball vat dog  alert narr      apple ball vat dog elephant

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I realize you re looking for a  deep  copy of an array  but if you just have a single level array you can use this   Copying a native JS Array is easy  Use the Array slice   method which creates a copy of part all of the array   var foo     a   b   c   d   e    var bar   foo slice      now foo and bar are 5 member arrays of  a   b   c   d   e   of course bar is a copy  not a reference    so if you did this next     bar push  f    alert  foo     foo join         alert  bar     bar join           you would now get   foo a  b  c  d  e bar a  b  c  d  e  f

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Everything in JavaScript is pass by reference  so if you want a true deep copy of the objects in the array  the best method I can think of is to serialize the entire array to JSON and then de-serialize it back

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I plan on releasing this code in the next version of jPaq  but until then  you can use this if your goal is to do a deep copy of arrays   Array prototype clone   function doDeepCopy        if doDeepCopy            var encountered                  a   this              b                           var item              levels     a this  b encountered 0  b  i 0                level   0              i   0              len   this length           while i  lt  len                item   levels level  a i               if Object prototype toString call item        object Array                      for var j   encountered length - 1  j  gt   0  j--                        if encountered j  a     item                            levels level  b push encountered j  b                           break                                                          if j  lt  0                        encountered push j                             a   item                          b                                                  levels level  b push j b                       levels level  i   i   1                      levels   level     a item  b j b  i 0                       i   -1                      len   item length                                              else                   levels level  b push item                              if   i    len  amp  amp  level  gt  0                    levels pop                    i   levels --level  i                  len   levels level  a length                                   return encountered 0  b            else           return this slice 0              The following is an example of how to call this function to do a deep copy of a recursive array      Create a recursive array to prove that the cloning function can handle it  var arrOriginal    1 2 3   arrOriginal push arrOriginal       Make a shallow copy of the recursive array  var arrShallowCopy   arrOriginal clone        Prove that the shallow copy isn t the same as a deep copy by showing that    arrShallowCopy contains arrOriginal  alert  It is      arrShallowCopy 3      arrOriginal          that arrShallowCopy contains arrOriginal         Make a deep copy of the recursive array  var arrDeepCopy   arrOriginal clone true       Prove that the deep copy really works by showing that the original array is    not the fourth item in arrDeepCopy but that this new array is  alert  It is          arrDeepCopy 3      arrOriginal  amp  amp  arrDeepCopy     arrDeepCopy 3           that arrDeepCopy contains itself and not arrOriginal       You can play around with this code here at JS Bin

User · Answer

extend true         a     c      b     That should do it for you

[javascript] (Deep) copying an array using jQuery

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