Javascript array length returns undefined

Question

I have a set of data that is being passed on by the PHP s json encode function  I m using the jQuery getJSON function to decode it      getJSON  url   function  data        console log data         The output looks like this in the console   Object  1  Object  2  Object  3  Object  4  Object  5  Object  6  Object  7  Object  8  Object  9  Object  10  Object    I can access each array by using data 1   data 2  etc  but to make it easier I thought of looping thought it so I can access all at once     getJSON  url   function  data        for  var i   0  len   data length  i  lt  len  i                do something             However I can t get this to work because the data length returns the value undefined  What is wrong and how can I fix it

User · Answer

One option is   Object keys myObject  length   Sadly it not works under older IE versions  under 9    If you need that compatibility  use the painful version   var key  count   0  for key in myObject      if myObject hasOwnProperty key         count

User · Answer

try this  Object keys data  length   If IE  lt  9  you can loop through the object yourself with a for loop  var len   0  var i   for  i in data        if  data hasOwnProperty i             len

User · Answer

An easy fix to this question is to add     in the start of your json file  and ending it with a      This solved it for me

User · Answer

It looks as though it s not an array but an arbitrary object  If you have control over the PHP serialization  you might be able to change that   As raina77ow pointed out  one way to do this in PHP would be by replacing something like this   json encode  something     with something like   json encode array values  something     But don t ignore the other answers here about Object keys   They should also accomplish what you want if you don t have the ability or the desire to change the serialization of your object

User · Answer

Objects don t have a  length property   A simple solution if you know you don t have to worry about hasOwnProperty checks  would be to do this   Object keys data  length    If you have to support IE 8 or lower  you ll have to use a loop  instead   var length  0  for var key in data        if data hasOwnProperty key            length

[javascript] Javascript : array.length returns undefined

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