Recursively looping through an object to build a property list

Question

Situation  I have a large object containing multiple sub and sub-sub objects  with properties containing multiple datatypes  For our purposes  this object looks something like this   var object         aProperty            aSetting1  1          aSetting2  2          aSetting3  3          aSetting4  4          aSetting5  5            bProperty            bSetting1                bPropertySubSetting   true                    bSetting2   bString             cProperty            cSetting   cString            I need to loop through this object and build a list of the keys that shows the hierarchy  so the list ends up looking like this   aProperty aSetting1 aProperty aSetting2 aProperty aSetting3 aProperty aSetting4 aProperty aSetting5 bProperty bSetting1 bPropertySubSetting bProperty bSetting2 cProperty cSetting   I ve got this function  which does loop through the object and spit out the keys  but not hierarchically   function iterate obj        for  var property in obj            if  obj hasOwnProperty property                 if  typeof obj property      object                     iterate obj property                              else                   console log property           obj property                                      Can somebody let me know how to do this  Here s a jsfiddle for you to mess with  http   jsfiddle net tbynA

User · Answer

You ll run into issues with this if the object has loop in its object graph  e g something like   var object         aProperty            aSetting1  1           object ref   object    In that case you might want to keep references of objects you ve already walked through  amp  exclude them from the iteration   Also you can run into an issue if the object graph is too deep like   var object       a    b    c                  You ll get too many recursive calls error  Both can be avoided   function iterate obj        var walked           var stack     obj  obj  stack            while stack length  gt  0                var item   stack pop            var obj   item obj          for  var property in obj                if  obj hasOwnProperty property                     if  typeof obj property      object                       var alreadyFound   false                    for var i   0  i  lt  walked length  i                                            if  walked i      obj property                                               alreadyFound   true                        break                                                              if   alreadyFound                                          walked push obj property                        stack push  obj  obj property   stack  item stack         property                                                          else                                       console log item stack         property         obj property                                                       iterate object

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The solution from Artyom Neustroev does not work on complex objects  so here is a working solution based on his idea   function propertiesToArray obj        const isObject   val   gt          typeof val      object   amp  amp   Array isArray val        const addDelimiter    a  b    gt          a      a    b     b       const paths    obj       head         gt            return Object entries obj               reduce  product   key  value     gt                                         let fullPath   addDelimiter head  key                      return isObject value                            product concat paths value  fullPath                         product concat fullPath                                     return paths obj

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This function can handle objects containing both objects and arrays of objects  Result will be one line per each single item of the object  representing its full path in the structure   Tested with http   haya2now jp data data json  Example result  geometry 6  obs 5  hayabusa2 delay from  function iterate obj  stack  prevType        for  var property in obj            if   Array isArray obj property                     console log property     L      obj property  length      is an array  with parent    prevType  stack               iterate obj property   stack    property    array              else               if   typeof obj property      string     amp  amp   typeof obj property      number                       if prevType     array                           console log stack          property      is an object  item of     prevType  stack                       iterate obj property   stack         property           object                      else                         console log stack      property     is     typeof obj property      with parent    prevType  stack                        iterate obj property   stack    property         object                                       else                   if prevType     array                         console log stack          property             obj property                       else                       console log stack      property              obj property                                                                                     iterate object       File   console log object

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An improved solution with filtering possibilities  This result is more convenient as you can refer any object property directly with array paths like        aProperty aSetting1    aProperty aSetting2    aProperty aSetting3    aProperty aSetting4    aProperty aSetting5    bProperty bSetting1 bPropertySubSetting    bProperty bSetting2    cProperty cSetting             Recursively searches for properties in a given object      Ignores possible prototype endless enclosures      Can list either all properties or filtered by key name         param  Object  object Object with properties      param  String  key Property key name to search for  Empty string to                         get all properties list       returns  String  Paths to properties from object root      function getPropertiesByKey object  key       var paths             iterate      object              return paths              Single object iteration  Accumulates to an outer  paths  array          function iterate object  path        var chainedPath       for  var property in object          if  object hasOwnProperty property              chainedPath             path length  gt  0             path         property             path   property           if  typeof object property      object                iterate              object property               chainedPath              chainedPath             else if             property     key              key length     0               paths push              chainedPath                                return paths

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I made a FIDDLE for you  I am storing a stack string and then output it  if the property is of primitive type   function iterate obj  stack            for  var property in obj                if  obj hasOwnProperty property                     if  typeof obj property      object                         iterate obj property   stack         property                     else                       console log property           obj property                            output   append     lt div  gt    text stack         property                                                    iterate object          UPDATE  17 01 2019  -  lt There used to be a different implementation  but it didn t work  See this answer for a prettier solution

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UPDATE  JUST USE JSON stringify to print objects on screen   All you need is this line    document body innerHTML     lt pre gt     JSON stringify ObjectWithSubObjects  null    t       lt  pre gt      This is my older version of printing objects recursively on screen    var previousStack           var output           function objToString obj  stack            for  var property in obj                var tab     amp nbsp  amp nbsp  amp nbsp  amp nbsp                if  obj hasOwnProperty property                     if  typeof obj property       object   amp  amp  typeof stack      undefined                         config   objToString obj property   property                     else                       if  typeof stack      undefined   amp  amp  stack     null  amp  amp  stack     previousStack                            output   output substring 0  output length - 1       remove last                           output    tab     lt span gt     property          obj property      lt  span gt  lt br   gt       insert property                         output              add last   again                       else                           if  typeof stack      undefined                                 output    stack          lt br   gt     tab                                                    output      lt span gt     property          obj property      lt  span gt  lt br   gt                            if  typeof stack      undefined                                 output                                                                             previousStack   stack                                                    return output          Usage    document body innerHTML   objToString ObjectWithSubObjects     Example output    cache  false position  fixed effect         fade  false     fall  true     Obviously this can be improved by adding comma s when needed and quotes from string values  But this was good enough for my case

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https   github com hughsk flat    var flatten   require  flat   flatten   key1        keyA   valueI     key2        keyB   valueII     key3    a    b    c  2                      key1 keyA    valueI         key2 keyB    valueII         key3 a b c   2        Just loop to get the indexes after

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This version is packed in a function that accepts a custom delimiter  filter  and returns a flat dictionary   function flatten source  delimiter  filter      var result          function flat obj  stack        Object keys obj  forEach function k          var s   stack concat  k         var v   obj k        if  filter  amp  amp  filter k  v   return       if  typeof v      object   flat v  s        else result s join delimiter     v             source        return result     var obj       a  1    b        c  2       flatten obj      lt - Object  a  1  b c  2  flatten obj           lt - Object  a  1  b c  2  flatten obj       function k  v    return k startsWith  a          lt - Object  b c  2

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Solution to flatten properties and arrays as well   Example input       obj1        prop1   value1       prop2   value2         arr1         value1        value2          Output    arr1 0     value1   arr1 1     value2   obj1 prop1    value1   obj1 prop2    value2    Source code   flatten object  path       res   undefined          if   Array isArray res               res                     if  object     null  amp  amp  typeof object      object               if  Array isArray object                   for  let i   0  i  lt  object length  i                        this flatten object i   path         i        res                              else                 const keys   Object keys object                for  let i   0  i  lt  keys length  i                        const key   keys i                    this flatten object key   path   path         key   key  res                                      else             if  path                  res path    object                           return res

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A simple path global variable across each recursive call does the trick for me    x000D   x000D  var object       aProperty        aSetting1  1      aSetting2  2      aSetting3  3      aSetting4  4      aSetting5  5        bProperty        bSetting1          bPropertySubSetting  true            bSetting2   bString         cProperty        cSetting   cString         function iterate obj  path           for  var property in obj        if  obj hasOwnProperty property           if  typeof obj property      object             let curpath       path  property           iterate obj property   curpath           else           console log path join              property           obj property                output   append     lt div  gt    text path join              property                        iterate object   x000D   lt script src  https   cdnjs cloudflare com ajax libs jquery 2 2 1 jquery min js  gt  lt  script gt   lt div id  output  gt  lt  div gt  x000D   x000D   x000D

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Suppose that you have a JSON object like   var example          prop1    value1        prop2      value2 0    value2 1         prop3               prop3 1    value3 1            The wrong way to iterate through its  properties    function recursivelyIterateProperties jsonObject        for  var prop in Object keys jsonObject             console log prop           recursivelyIterateProperties jsonObject prop              You might be surprised of seeing the console logging 0  1  etc  when iterating through the properties of prop1 and prop2 and of prop3 1  Those objects are sequences  and the indexes of a sequence are properties of that object in Javascript   A better way to recursively iterate through a JSON object properties would be to first check if that object is a sequence or not   function recursivelyIterateProperties jsonObject        for  var prop in Object keys jsonObject             console log prop           if    typeof jsonObject prop        string                amp  amp    jsonObject prop  instanceof Array                     recursivelyIterateProperties jsonObject prop                              If you want to find properties inside of objects in arrays  then do the following   function recursivelyIterateProperties jsonObject         if  jsonObject instanceof Array            for  var i   0  i  lt  jsonObject length    i                recursivelyIterateProperties jsonObject i                       else if  typeof jsonObject       object             for  var prop in Object keys jsonObject                 console log prop               if    typeof jsonObject prop        string                      recursivelyIterateProperties jsonObject prop

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I ll provide a solution too  using recursion  Commented lines to clarify things  It works well for its purpose right now   x000D   x000D     works only if the value is a dictionary or something specified below  and adds all keys in nested objects and outputs them  const example       city   foo     year  2020    person        name   foo       age  20      deeper          even deeper            key   value            arr   1  2              a  1            b  2                                   var flat               store keys var depth    0         depth  used later var path      obj      base path to be added onto  specified using the second parameter of flatKeys   let flatKeys    t  name    gt      path   name   name   path      if specified  set the path    for  const k in t        const v   t k       let type   typeof v          store the type value s type     switch  type            case  string               these are the specified cases for which a key will be added        case  number               specify more if you want       case  array            flat push path         k       add the complete path to the array         break        case  object           flat push path         k          path          k          flatKeys v           break              return flat      let flattened   flatKeys example   example       the second argument is what the root path should be  for convenience  console log flattened   keys      flattened length   x000D   x000D   x000D

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Here is a simple solution  This is a late answer but may be simple one-  x000D   x000D  const data       city   foo     year  2020    person        name          firstName   john         lastName   doe             age  20      type          a  2        b  3        c            d  4          e  5                       function getKey obj  res       parent           const keys   Object keys obj            Loop throw the object keys and check if there is any object there      keys forEach key   gt        if  typeof obj key       object              Generate the heirarchy       parent   res push    parent    key      res push key         else            If object found then recursively call the function with updpated parent       let newParent   parent      parent    key     key        getKey obj key   res  newParent                       const result        getKey data  result        console log result   x000D   as-console-wrapper min-height  100  important  top  0  x000D   x000D   x000D

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With a little help from lodash            For object  or array   obj   recursively search all keys    and generate unique paths for every key in the tree      param  Object  obj     param  String  prev     export const getUniqueKeyPaths    obj  prev         gt    flatten    Object    entries obj     map entry   gt        const  k  v    entry     if  v     null  amp  amp  typeof v      object           const newK   prev      prev    k        k            Must include the prev and current k before going recursive so we don t lose keys whose values are arrays or objects       return  newK     getUniqueKeyPaths v  newK             return    prev    k

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You can use a recursive Object keys to achieve that  var keys       const findKeys    object  prevKey         gt      Object keys object  forEach  key    gt        const nestedKey   prevKey          key      prevKey    key        if  typeof object key       object   return keys push nestedKey       findKeys object key   nestedKey          findKeys object   console log keys   Which results in this array      quot aProperty aSetting1 quot      quot aProperty aSetting2 quot      quot aProperty aSetting3 quot      quot aProperty aSetting4 quot      quot aProperty aSetting5 quot      quot bProperty bSetting1 bPropertySubSetting quot      quot bProperty bSetting2 quot      quot cProperty cSetting quot     To test  you can provide your object  object       aProperty        aSetting1  1      aSetting2  2      aSetting3  3      aSetting4  4      aSetting5  5        bProperty        bSetting1          bPropertySubSetting  true            bSetting2   quot bString quot         cProperty        cSetting   quot cString quot

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You don t need recursion   The following function function which will output the entries in the order of least deep to the most deep with the value of the key as a  key  value  array   function deepEntries  obj         use-strict       var allkeys  curKey        len   0  i   -1  entryK       function formatKeys  entries           entryK   entries length         len    entries length         while  entryK--           entries entryK  0    curKey JSON stringify entries entryK  0               return entries            allkeys   formatKeys  Object entries obj          while    i     len          if  typeof allkeys i  1       object   amp  amp  allkeys i  1      null               curKey   allkeys i  0                     Array prototype push apply                  allkeys                  formatKeys  Object entries allkeys i  1                                  return allkeys      Then  to output the kind of results you are looking for  just use this   function stringifyEntries allkeys       return allkeys reduce function acc  x           return acc   acc amp  amp   n   x 0                    If your interested in the technical bits  then this is how it works  It works by getting the Object entries of the obj object you passed and puts them in array allkeys  Then  going from the beggining of allkeys to the end  if it finds that one of allkeys entries value s is an object then it gets that entrie s key as curKey  and prefixes each of its own entries keys with curKey before it pushes that resulting array onto the end of allkeys  Then  it adds the number of entries added to allkeys to the target length so that it will also go over those newly added keys too   For example  observe the following    x000D   x000D   lt script gt  x000D  var object     x000D      aProperty    x000D          aSetting1  1  x000D          aSetting2  2  x000D          aSetting3  3  x000D          aSetting4  4  x000D          aSetting5  5 x000D         x000D      bProperty    x000D          bSetting1    x000D              bPropertySubSetting   true x000D             x000D          bSetting2   bString  x000D         x000D      cProperty    x000D          cSetting   cString  x000D        x000D    x000D  document write  x000D        lt pre gt     stringifyEntries  deepEntries object        lt  pre gt   x000D     x000D  function deepEntries  obj     debugger  x000D       use-strict   x000D      var allkeys  curKey        len   0  i   -1  entryK  x000D   x000D      function formatKeys  entries    x000D         entryK   entries length  x000D         len    entries length  x000D         while  entryK--  x000D           entries entryK  0    curKey JSON stringify entries entryK  0        x000D         return entries  x000D        x000D      allkeys   formatKeys  Object entries obj     x000D   x000D      while    i     len  x000D          if  typeof allkeys i  1       object   amp  amp  allkeys i  1      null   x000D              curKey   allkeys i  0         x000D              Array prototype push apply  x000D                  allkeys  x000D                  formatKeys  Object entries allkeys i  1     x000D                 x000D            x000D      return allkeys  x000D    x000D  function stringifyEntries allkeys   x000D      return allkeys reduce function acc  x   x000D          return acc   acc amp  amp   n   x 0   x000D              x000D     x000D   lt  script gt  x000D   x000D   x000D    Or  if you only want the properties  and not the objects that have properties  then you can filter then out like so   deepEntries object  filter function x  return typeof x 1       object       Example    x000D   x000D   lt script gt  x000D  var object     x000D      aProperty    x000D          aSetting1  1  x000D          aSetting2  2  x000D          aSetting3  3  x000D          aSetting4  4  x000D          aSetting5  5 x000D         x000D      bProperty    x000D          bSetting1    x000D              bPropertySubSetting   true x000D             x000D          bSetting2   bString  x000D         x000D      cProperty    x000D          cSetting   cString  x000D        x000D    x000D  document write   lt pre gt     stringifyEntries  x000D      deepEntries object  filter function x   x000D         return typeof x 1       object   x000D         x000D        lt  pre gt     x000D  function deepEntries  obj     debugger  x000D       use-strict   x000D      var allkeys  curKey        len   0  i   -1  entryK  x000D   x000D      function formatKeys  entries    x000D         entryK   entries length  x000D         len    entries length  x000D         while  entryK--  x000D           entries entryK  0    curKey JSON stringify entries entryK  0        x000D         return entries  x000D        x000D      allkeys   formatKeys  Object entries obj     x000D   x000D      while    i     len  x000D          if  typeof allkeys i  1       object   amp  amp  allkeys i  1      null   x000D              curKey   allkeys i  0         x000D              Array prototype push apply  x000D                  allkeys  x000D                  formatKeys  Object entries allkeys i  1     x000D                 x000D            x000D      return allkeys  x000D    x000D  function stringifyEntries allkeys   x000D      return allkeys reduce function acc  x   x000D          return acc   acc amp  amp   n   x 0   x000D              x000D     x000D   lt  script gt  x000D   x000D   x000D    Browser Compatibility  The above solution will not work in IE  rather it will only work in Edge because it uses the Object entries function  If you need IE9  support  then simply add the following Object entries polyfill to your code  If you  for some reason beyond me  actually do need IE6  support  then you will also need an Object keys and JSON stringify polyfill  neither listed here  so find it somewhere else    if   Object entries    Object entries   function  obj        var ownProps   Object keys  obj            i   ownProps length          resArray   new Array i      preallocate the Array     while  i--        resArray i     ownProps i   obj ownProps i          return resArray

[javascript] Recursively looping through an object to build a property list

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