Retrieving a property of a JSON object by index

Question

Assuming this JSON object     var obj          set1    1  2  3        set2    4  5  6  7  8        set3    9  10  11  12       The  set2  property may be retrieved like so   obj  set2     Is there a way to retrieve the  set2  property by index  It is the second property of the JSON object  This does not work  of course      obj 1      So  let s say that I want to retrieve the second property of the JSON object  but I don t know its name - how would I do it then     Update  Yes  I understand that objects are collections of unordered properties  But I don t think that the browsers mess with the  original  order defined by the JSON literal   string

User · Answer

it is quite simple      x000D   x000D  var obj     x000D       set1    1  2  3   x000D       set2    4  5  6  7  8   x000D       set3    9  10  11  12  x000D     x000D   x000D  jQuery each obj  function i  val    x000D   console log i       set1  x000D   console log val       1  2  3  x000D      x000D   lt script src  https   cdnjs cloudflare com ajax libs jquery 3 3 1 jquery min js  gt  lt  script gt  x000D   x000D   x000D

User · Answer

I know this is an old question but I found a way to get the fields by index  You can do it by using the Object keys method   When you call the Object keys method it returns the keys in the order they were assigned  See the example below   I tested the method below in the following browsers    Google Chrome version 43 0 Firefox version 33 1 Internet Explorer version 11   I also wrote a small extension to the object class so you can call the nth key of the object using getByIndex    x000D   x000D     Function to get the nth key from the object x000D  Object prototype getByIndex   function index    x000D    return this Object keys this  index    x000D     x000D   x000D  var obj1     x000D     set1    1  2  3   x000D     set2    4  5  6  7  8   x000D     set3    9  10  11  12  x000D     x000D   x000D  var obj2     x000D     set2    4  5  6  7  8   x000D     set1    1  2  3   x000D     set3    9  10  11  12  x000D     x000D   x000D  log  -- Obj1 --    x000D  log obj1   x000D  log Object keys obj1    x000D  log obj1 getByIndex 0    x000D   x000D   x000D  log  -- Obj2 --    x000D  log obj2   x000D  log Object keys obj2    x000D  log obj2 getByIndex 0    x000D   x000D   x000D     Log function to make the snippet possible x000D  function log x    x000D    var d   document createElement  div    x000D    if  typeof x      object     x000D      x   JSON stringify x  null  4   x000D      x000D    d textContent  x  x000D    document body appendChild d   x000D    x000D   x000D   x000D

User · Answer

My solution   Object prototype   index function index                            var i -1                            for  var key in this                                 if  this hasOwnProperty key   amp  amp  typeof this key      function                                        i                                                                     if  i gt  index                                     return this key                                                                                                 return null                             aObj   jack  3   peter  4   5   col    kk  function   alert  hell       till   ding    alert aObj   index 4

User · Answer

Here you can access  set2  property following       var obj              set1    1  2  3            set2    4  5  6  7  8            set3    9  10  11  12              var output   Object keys obj  1     Object keys return all the keys of provided object as Array

User · Answer

Objects in JavaScript are collections of unordered properties  Objects are hashtables    If you want your properties to be in alphabetical order  one possible solution would be to create an index for your properties in a separate array  Just a few hours ago  I answered a question on Stack Overflow which you may want to check out    Iterating over a JavaScript object in sort order based on particular key value of a child object   Here s a quick adaptation for your object1   var obj          set1    1  2  3        set2    4  5  6  7  8        set3    9  10  11  12      var index           build the index for  var x in obj       index push x         sort the index index sort function  a  b           return a    b   0    a  gt  b   1   -1           Then you would be able to do the following   console log obj index 1       The answer I cited earlier proposes a reusable solution to iterate over such an object  That is unless you can change your JSON to as  Jacob Relkin suggested in the other answer  which could be easier     1 You may want to use the hasOwnProperty   method to ensure that the properties belong to your object and are not inherited from Object prototype

User · Answer

Jeroen Vervaeke s answer is modular and the works fine  but it can cause  problems if it is using with jQuery or other libraries that count on  object-as-hashtables  feature of Javascript    I modified it a little to make usable with these libs   function getByIndex obj  index      return obj Object keys obj  index

User · Answer

No  there is no way to access the element by index in JavaScript objects   One solution to this if you have access to the source of this JSON  would be to change each element to a JSON object and stick the key inside of that object like this   var obj           key   set1    data   1  2  3          key   set2    data   4  5  6  7  8          key   set3    data   9  10  11  12        You would then be able to access the elements numerically   for var i   0  i  lt  obj length  i          var k   obj i   key        var data   obj i   data          do something with k or data

User · Answer

You could iterate over the object and assign properties to indexes  like this   var lookup       var i   0   for  var name in obj        if  obj hasOwnProperty name             lookup i    obj name           i             lookup 2        However  as the others have said  the keys are in principle unordered  If you have code which depends on the corder  consider it a hack  Make sure you have unit tests so that you will know when it breaks

User · Answer

Simple solution  just one line    var obj          set1    1  2  3        set2    4  5  6  7  8        set3    9  10  11  12      obj   Object values obj    obj 1

User · Answer

There is no  second property  -- when you say var obj            the properties inside the braces are unordered   Even a  for  loop walking through them might return them in different orders on different JavaScript implementations

User · Answer

This could be done in python as follows  Form the command as a string and then execute     context          whoami    abc        status    0        curStep   2       parentStepStatus              step1     stepStatus   0   stepLog    f1 log              step2     stepStatus   0   stepLog    f2 log            def punc              i   1           while  i  lt  10                 x    print      context       parentStepStatus          s      step s    i                      exec x                i  1 punc

[javascript] Retrieving a property of a JSON object by index?

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