How to get object length

Question

Is there any built-in function that can return the length of an object   For example  I have a      a  1  b  2  c  3   which should return 3  If I use a length it returns undefined   It could be a simple loop function  but I d like to know if there s a built-in function   There is a related question  Length of a JSON object  - in the chosen answer the user advises to transform object into an array  which is not pretty comfortable for my task

User · Answer

This should do it   Object keys a  length   However  Object keys is not supported in IE8 and below  Opera and FF 3 6 and below   Live demo  http   jsfiddle net simevidas nN84h

User · Answer

So one does not have to find and replace the Object keys method  another approach would be this code early in the execution of the script   if  Object keys      Object keys   function obj          return   map obj  function v  k              return k

User · Answer

Here s a jQuery-ised function of Innuendo s answer  ready for use     extend       keyCount   function o            if typeof o     object                 var i  count   0              for i in o                    if o hasOwnProperty i                         count                                                return count            else               return false                        Can be called like this   var cnt     keyCount   foo     bar       cnt   1

User · Answer

If you want to avoid new dependencies you could make your own smart objects  Of course only if you want to do more that just get it s size   MyNeatObj   function  obj      var length   null     this size   function          if  length     null          length   0        for  var key in obj  length              return length         var thingy   new MyNeatObj originalObj   thingy size

User · Answer

You may use something like Lodash lib and   toLength object  should give you the length of your object

User · Answer

Summarizing all together  here is a universal function  including ie8 support     x000D   x000D  var objSize   function obj    x000D      var count   0  x000D       x000D      if  typeof obj     object     x000D       x000D          if  Object keys    x000D              count   Object keys obj  length  x000D            else if  window      x000D              count     keys obj  length  x000D            else if  window      x000D              count     map obj  function     return 1     length  x000D            else   x000D              for  var key in obj  if  obj hasOwnProperty key   count    x000D            x000D           x000D        x000D       x000D      return count  x000D     x000D   x000D  document write objSize   a  1  b  2  c  3      x000D     3 x000D   x000D   x000D

User · Answer

Can be done easily with   map     var len     map a  function n  i    return i     length

User · Answer

Have you taken a look at underscore js  http   underscorejs org docs underscore html   It s a utility library with a lot of useful methods   There is a collection size method  as well as a toArray method  which may get you what you need     size  one   1  two   2  three   3      gt  3

User · Answer

For those coming here to find the item count of something that is already a jQuery object   length is what you are looking for   Example   len       divID   length  alert len

User · Answer

Also can be done in this way   Object entries obj  length     For example   let obj     a  1  b  2     console log Object entries obj  length       gt  2    Object entries obj    gt       a   1       b   2

User · Answer

You might have an undefined property in the object  If using the method of Object keys data  length is used those properties will also be counted    You might want to filter them out out   Object keys data  filter  v    gt   return data v      undefined   length

User · Answer

For browsers supporting Object keys   you can simply do   Object keys a  length    Otherwise  notably in IE  lt  9   you can loop through the object yourself with a for  x in y  loop   var count   0  var i   for  i in a        if  a hasOwnProperty i             count              The hasOwnProperty is there to make sure that you re only counting properties from the object literal  and not properties it  inherits  from its prototype

User · Answer

One more answer    x000D   x000D  var j       uid   1   name   Bingo Boy    profile img   funtimes jpg     uid   2   name   Johnny Apples    profile img   badtime jpg      x000D   x000D  obj   Object keys j  length  x000D  console log obj  x000D   x000D   x000D

User · Answer

You could add another name value pair of length  and increment decrement it appropriately  This way  when you need to query the length  you don t have to iterate through the entire objects properties every time  and you don t have to rely on a specific browser or library  It all depends on your goal  of course

User · Answer

In jQuery i ve made it in a such way   len   function obj        var L 0        each obj  function i  elem            L                return L

[javascript] How to get object length

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