I have an array of objects that I am trying to sort but it does not seem to be working. Some objects in the array have a orderNum property which I am targeting to sort. But not all objects have this property.

I want the objects with the orderNum property to be sorted to the top positions in the array.

Here is a fiddle to what i have tried: /

Here is my javascript:

var data = {
  "attributes": [
    {
        "value": "123-456-7890",
        "name": "phone"
    },
    {
        "value": "[email protected]",
        "name": "email"
    },
    {
        "value": "Gotham",
        "name": "city",
        "orderNum": 1
    },
    {
        "value": "12",
        "name": "ID"
    },
    {
        "value": "Batman",
        "name": "Super Hero",
        "orderNum": 2
    }
  ]
};

data.attributes.sort( function (a, b) {
  if (a.orderNum < b.orderNum) {
    return -1;
  }
  if (a.orderNum > b.orderNum) {
    return 1;
  }

  return 0;
});

console.log(data);

I have an array of objects that I am trying to sort but it does not seem to be working. Some objects in the array have a orderNum property which I am targeting to sort. But not all objects have this property.

I want the objects with the orderNum property to be sorted to the top positions in the array.

Here is a fiddle to what i have tried: http://jsfiddle.net/7D8sN/

Here is my javascript:

var data = {
  "attributes": [
    {
        "value": "123-456-7890",
        "name": "phone"
    },
    {
        "value": "[email protected]",
        "name": "email"
    },
    {
        "value": "Gotham",
        "name": "city",
        "orderNum": 1
    },
    {
        "value": "12",
        "name": "ID"
    },
    {
        "value": "Batman",
        "name": "Super Hero",
        "orderNum": 2
    }
  ]
};

data.attributes.sort( function (a, b) {
  if (a.orderNum < b.orderNum) {
    return -1;
  }
  if (a.orderNum > b.orderNum) {
    return 1;
  }

  return 0;
});

console.log(data);

• javascript
• arrays
• sorting

• 2 Works for me. You really should have a value for orderNum for the undefined ones. Your getting odd results because you are comparing undefined and your sort function is returning 0 when you compare ones with values to ones without values. – jeremy Commented Apr 25, 2014 at 18:48
• 1 @jeremy That's the whole point of his question, he wants to know how to avoid getting odd results for elements with no orderNum. – Barmar Commented Apr 25, 2014 at 18:56

4 Answers 4

Check if the property exists in your sort function.

data.attributes.sort( function (a, b) {
    if ((typeof b.orderNum === 'undefined' && typeof a.orderNum !== 'undefined') || a.orderNum < b.orderNum) {
        return -1;
    }
    if ((typeof a.orderNum === 'undefined' && typeof b.orderNum !== 'undefined') || a.orderNum > b.orderNum) {
        return 1;
    }

    return 0;
});

You have to check specifically for the property being undefined. Otherwise, both tests return false, so you fall through to return 0 and treat them as equal to everything.

data.attributes.sort( function (a, b) {
  if (a.orderNum === undefined || a.orderNum < b.orderNum) {
    return -1;
  }
  if (b.orderNum === undefined || b.orderNum < a.orderNum) {
    return 1;
  }

  return 0;
});

You can check whether each object has the property with hasOwnProperty("orderNum") and then sort them accordingly. If one has it, and the other does not, then the one with it gets put first. I made the assumption that you were sorting with orderNum ascending.

JSFiddle: http://jsfiddle.net/dshell/RFr5N/

data.attributes.sort( function (a, b) {
    if ((a.hasOwnProperty("orderNum")) && (b.hasOwnProperty("orderNum")))
    {
        return a.orderNum - b.orderNum;
    }
    else if (a.hasOwnProperty("orderNum"))
    {
        return -1;
    }
    else if (b.hasOwnProperty("orderNum"))
    {
        return 1;
    }

    return 0;
});

What you need is to 'normalize' your input :

data.attributes.sort( function (a, b) {
   var aOrderNum = ( a.orderNum === undefined ) ? -1 : a.orderNum ;
   var bOrderNum = ( b.orderNum === undefined ) ? -1 : b.orderNum ;
   return aOrderNum - bOderNum;
 });