JavaScript - Dictionary is empty - Stack Overflow

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I'm using Appcelerator and I want to know if my dictionary in JS is empty.

I've tried this:

var options = {};

// Option 1
Object.keys(options).length
1

//Option 2
isEmpty(options)
false

function isEmpty(ob){
      for(var i in ob){ if(ob.hasOwnProperty(i)){return false;}}
      return true;
}

//Option 3
JSON.stringify(options) === '{}'
false

I'm using Appcelerator and I want to know if my dictionary in JS is empty.

I've tried this:

var options = {};

// Option 1
Object.keys(options).length
1

//Option 2
isEmpty(options)
false

function isEmpty(ob){
      for(var i in ob){ if(ob.hasOwnProperty(i)){return false;}}
      return true;
}

//Option 3
JSON.stringify(options) === '{}'
false

• javascript
• dictionary
• appcelerator
• appcelerator-titanium

Share Improve this question Follow edited Feb 10, 2016 at 13:20 Fokke Zandbergen 3,86611 gold badge1313 silver badges2828 bronze badges asked Feb 8, 2016 at 13:00 amurciaamurcia 7911010 silver badges2727 bronze badges 9

• What does console.log.log(options) show you? The first option is telling you there is one property, so what is it? Log it and see. – nnnnnn Commented Feb 8, 2016 at 13:03
• I don't know why shows one property. The console shows: options = {} – amurcia Commented Feb 8, 2016 at 13:06
• 1 But what is the key? Log Object.keys(options), not the .length, so we can see what the first key is. Could that property (whatever it is) have a value that was set to undefined, or to a function? Either would be ignored by JSON. stringify. – nnnnnn Commented Feb 8, 2016 at 13:23
• 1 Thank you, you're right. I had a key with undefined value. – amurcia Commented Feb 8, 2016 at 14:44
• 1 @FokkeZandbergen done! – amurcia Commented Feb 10, 2016 at 13:28

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1 Answer 1

Sorted by: Reset to default 3

Finally I found the problem: I added one key with value 'undefined' and the JSON.stringify() function didn't show me that key.

So, this function Object.keys(options).length works perfectly.

Caution with keys with value 'undefined', check this with this function Object.keys(options) because JSON.stringify return an empty dictionary {}

var dict = {
   cat: undefined
}

Ti.API.debug("Dict: " + JSON.stringify(dict)) >  Dict: {}
Ti.API.debug("Keys: " + Object.keys(options).length) > Keys: 1
Ti.API.debug("Keys str: " + Object.keys(options)) > Keys: cat

var dict = {}

Ti.API.debug("Dict: " + JSON.stringify(dict)) >  Dict: {}
Ti.API.debug("Keys: " + Object.keys(options).length) > Keys: 0
Ti.API.debug("Keys str: " + Object.keys(options)) > Keys:

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