I've declared an array of empty elements, how can I check which elements remain empty?

Question

As title says, I have the following array:

var viewModel = [{}, {}, {}];

At some point in my code I may populate the 2nd element:

var viewModel = [{}, { "test" : "value" }, {}];

I need a way of evaluating if the elements are empty or not. In the above case, elements 0 and 2 will evalute to true, and element 1 will evaluate to false.

What I've Tried

I've tried comparing each element to undefined and ' ' to no avail. I know could probably check for the test property of each element (if it exists it's not empty) but I ideally wanted a way of determining this independent of any property names.

(I've tagged jQuery as I'm open to jQuery suggestions).

Your code probably isn't working as the array element contains an empty object, it isn't empty or undefined. You might want to look at this: http://api.jquery.com/jQuery.isEmptyObject/ or the answers here: http://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object — Joe, May 27 '14 at 14:47
@Joe - Brilliant!! Exactly what I was after. Please post as the answer and I'll mark accordingly. Thanks very much mate. — , May 27 '14 at 14:49
It's ok, I'd just be re-posting what someone else had put. Glad it helped you though! — Joe, May 27 '14 at 14:50

score 1 · Answer 1 · answered May 27 '14 at 15:01

1

{} === {} //false

JSON.stringify({}) === JSON.stringify({}) //true

JSON.stringify(myArray[0]) === JSON.stringify({}) //true

This might come handy in your particular case may be. I havent thought much about the loopholes also.

answered May 27 '14 at 15:01

sabithpocker

15,274
1
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75

score 0 · Answer 2 · answered May 27 '14 at 14:52

How about this

// function to check if object is empty
function isEmpty(obj) {
    return Object.keys(obj).length === 0;
}

var viewModel = [{}, { "test" : "value" }, {}];
// loop
for(var i = 0; i < viewModel.length; i++)
{ 
    // returns true if empty, otherwise false
    console.log(isEmpty(viewModel[i]));
}

score 0 · Answer 3 · answered May 27 '14 at 14:52

0

You can count the elements that are in each object by looping through the array.

for(var i = 0; i < test.length; i++){
  if(Object.keys(test).length == 0){
    //element array[i] is empty!
  }
}

This is only in browsers supporting Ecma-script 5.

answered May 27 '14 at 14:52

Wouter Vandersyppe

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1
7

score 0 · Answer 4 · answered May 27 '14 at 15:02

Takes an array of objects and returns a new array of true/false values

function isObjectEmpty(arr) {
  return arr.map(function (el) {
    return Object.keys(el).length === 0 ? true : false;
  });
}

isObjectEmpty(yourExampleArray) // [true, false, true]

Demo

I've declared an array of empty elements, how can I check which elements remain empty?

4 Answers4