is this object empty, Javascript

Question

I have an ajax system set up. When the MySQL query returns no data, I need it to pass an empty object back. I create a node called 'data' in the php script and even when the query returns no data I pass $data['success'] = 1.

The trick is I can't figure out how to check to see if the query was returned data or not.

I have tried...

// sub responseObj.data for responseObj.data[0] for the following if's
if(responseObj.data[0].length == -1)  

if(responseObj.data[0] == null)

if(responseObj == undefined)
//edit: added this...
if(!responseObj.data[0])

and I've really lost tack of any other various snippet's i've tried.

EDIT: adding xml generated that is passed to my script
XML - returning zero results

<response_myCallbackFunction>  
  <success>1</success>  
<response_myCallbackFunction>

XML - returning a populated query

<response_myCallbackFunction>  
  <data> 
  <random_data>this is data</random_data>  
  </data>  
  <success>1</success>  
<response_myCallbackFunction>

Is there a way to check to see if an object is empty in javascript?

-thanks

can you add a snippet from your php for what you are returning — robjmills
– robjmills, Commented Dec 22, 2009 at 16:02
possible duplicate of How do I test for an empty Javascript object from JSON? — Derek Adair
– Derek Adair, Commented Nov 6, 2013 at 16:46

Derek Adair · Accepted Answer · 2010-12-18 02:11:22Z

7

Obj.hasOwnProperty('blah') does not seem to work for checking to see if the property exists.

function isEmptyObj(obj){
  for(var i in obj){
    return false;
  }
  return true;
}

isEmptyObj({a:1}); //returns true

isEmptyObj({}); //returns false

edited Dec 18, 2010 at 2:11

answered Dec 22, 2009 at 16:43

Derek Adair

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Comments

Chris Frederick · Accepted Answer · 2011-07-27 22:42:19Z

3

You could try

if( responseObj["data"] ) {
   // do stuff with data
}

or

if( responseObj.hasOwnProperty("data") && responseObj.data ) {
   // do stuff with data
}

edited Jul 27, 2011 at 22:42

Chris Frederick

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answered Dec 22, 2009 at 16:02

Jared

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4 Comments

Derek Adair Over a year ago

nope... I thought responseObj.hasOwnProperty("data") would have done it... but no go... grr

Derek Adair Over a year ago

ahh... I just read Obj.hasOwnProperty('property') cannot check for the existence of a property. ( javascript.about.com/od/reference/g/shasownproperty.htm )

Jared Over a year ago

not sure where you are looking... hasOwnProperty() can check for existence of a property (hence the name). Would suggest NOT reading about javascript on about.com :D

Jared Over a year ago

sure, Mozilla Developer Center has some great docs: developer.mozilla.org/En/…

zincorp · Accepted Answer · 2009-12-22 17:52:15Z

1

if(typeof responseObj.data != 'undefined') {
   // code goes here
}

answered Dec 22, 2009 at 17:52

zincorp

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Comments

vsync · Accepted Answer · 2011-06-08 17:09:03Z

1

for ES5 you have getOwnPropertyNames :

var o = { a:1, b:2, c:3 };
Object.getOwnPropertyNames(o).length // 3

answered Jun 8, 2011 at 17:09

vsync

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Comments

NickFitz · Accepted Answer · 2009-12-22 17:21:11Z

0

If responseObj is the XML Document object (from the xhr.responseXML property), then:

if (responseObj.getElementsByTagName("data").length > 0) {
    // do stuff...
}

If responseObj is a JavaScript object:

if (responseObj.data) {
    // do stuff...
}

answered Dec 22, 2009 at 17:21

NickFitz

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