How to inspect Javascript Objects

Question

How can I inspect an Object in an alert box  Normally alerting an Object just throws the nodename   alert document     But I want to get the properties and methods of the object in the alert box  How can I achieve this functionality  if possible  Or are there any other suggestions   Particularly  I am seeking a solution for a production environment where console log and Firebug are not available

User · Answer

Use console dir object  and the Firebug plugin

User · Answer

How about alert JSON stringify object   with a modern browser   In case of TypeError  Converting circular structure to JSON  here are more options  How to serialize DOM node to JSON even if there are circular references   The documentation  JSON stringify   provides info on formatting or prettifying the output

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This is blatant rip-off of Christian s excellent answer  I ve just made it a bit more readable          objectInspector digs through a Javascript object    to display all its properties        param object - a Javascript object to inspect     param result - a string of properties with datatypes        return result - the concatenated description of all object properties     function objectInspector object  result        if  typeof object     object           return  Invalid object       if  typeof result     undefined           result            if  result length  gt  50          return   RECURSION TOO DEEP  ABORTING          var rows           for  var property in object            var datatype   typeof object property            var tempDescription   result     property              tempDescription         datatype      gt             if  datatype     object               tempDescription     object    objectInspector object property  result                else             tempDescription    object property            rows push tempDescription          Close for      return rows join result   n       End objectInspector

User · Answer

There are few methods      1  typeof tells you which one of the 6 javascript types is the object    2  instanceof tells you if the object is an instance of another object   3  List properties with for var k in obj   4  Object getOwnPropertyNames  anObjectToInspect     5  Object getPrototypeOf  anObject    6  anObject hasOwnProperty aProperty     In a console context  sometimes the  constructor or  prototype maybe useful    console log anObject constructor     console log anObject prototype

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Use your console   console log object     Or if you are inspecting html dom elements use console dir object   Example   let element   document getElementById  alertBoxContainer    console dir element     Or if you have an array of js objects you could use   console table objectArr     If you are outputting a lot of console log objects  you can also write   console log   objectName1     console log   objectName2       This will help you label the objects written to console

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Here is my object inspector that is more readable  Because the code takes to long to write down here you can download it at http   etto-aa-js googlecode com svn trunk inspector js  Use like this    document write inspect object

User · Answer

The for-in loops for each property in an object or array  You can use this property to get to the value as well as change it   Note  Private properties are not available for inspection  unless you use a  spy   basically  you override the object and write some code which does a for-in loop inside the object s context   For in looks like   for  var property in object  loop      Some sample code   function xinspect o i       if typeof i   undefined  i         if i length gt 50 return   MAX ITERATIONS        var r         for var p in o           var t typeof o p           r push i     p       t      gt     t   object     object   xinspect o p  i         o p                  return r join i   n          example of use  alert xinspect document      Edit  Some time ago  I wrote my own inspector  if you re interested  I m happy to share   Edit 2  Well  I wrote one up anyway

User · Answer

var str       for var k in obj      if  obj hasOwnProperty k     omit this test if you want to see built-in properties         str    k           obj k      n   alert str

[javascript] How to inspect Javascript Objects

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