Looping through an object and a nested for loop that loops through array

Question

I am looping through an object and then upon each object I am comparing it to the items in my array in hopes to then push the objects that are not the same into my ItemsNotInObject array. Hopefully someone can shine some light on this for me. Thank you in advance.

var obj = {a:1, a:2, a:3};
var array = [1, 4, 2, 5, 6];
var ItemsNotInObject = [];


for (var prop in obj) {
    for(var i = 0, al = array.length; i < al; i++){
       if( obj[prop].a !== array[i] ){
           ItemsNotInObject.push(array[i]);
        }
    }
}

console.log(ItemsNotInObject);
//output of array: 1 , 4 , 2 , 5, 6

//output desired is: 4 , 5 , 6

Property names must be different. {a:1, a:2, a:3} becomes {a:3}. — Oriol
– Oriol, Commented Jun 24, 2015 at 23:18

AmmarCSE · Accepted Answer · 2015-06-24 23:37:27Z

1

Your object has duplicate keys. This is not a valid JSON object. Make them unique
Do not access the object value like obj[prop].a, obj[prop] is a
Clone the original array.
Use indexOf() to check if the array contains the object property or not.
If it does, remove it from the cloned array.

var obj = {
  a: 1,
  b: 2,
  c: 3
};
var array = [1, 4, 2, 5, 6];
var ItemsNotInObject = array.slice(); //clone the array

for (var prop in obj) {
  if (array.indexOf(obj[prop]) != -1) {
    for (var i = 0; i < ItemsNotInObject.length; i++) {
      if (ItemsNotInObject[i] == obj[prop]) {
        ItemsNotInObject.splice(i, 1); //now simply remove it because it exists
      }
    }
  }
}

console.log(ItemsNotInObject);

edited Jun 24, 2015 at 23:37

answered Jun 24, 2015 at 23:31

AmmarCSE

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1 Comment

Eduardo La Hoz Miranda Over a year ago

This was such a simple fix, I thank you very much, king gentleman. I did indeed mess up the writing of my json, it's really in this form obj = [{key:value},{key:value}, {etc}]; But, nevertheless, slice saved my life. Thank you again.

eaktas · Accepted Answer · 2015-06-24 23:31:18Z

1

If you can make your obj variable an array, you can do it this way;

var obj = [1, 2, 3];
var array = [1, 4, 2, 5, 6];
var ItemsNotInObject = [];


    for(i in array){
       if( obj.indexOf(array[i]) < 0) ItemsNotInObject.push(array[i]);
    }

console.log(ItemsNotInObject);

if the obj variable needs to be json object please provide the proper form of it so i can change the code according to that.

answered Jun 24, 2015 at 23:31

eaktas

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1 Comment

Eduardo La Hoz Miranda Over a year ago

Thanks for the help, but turning into an array is not an option inside my application.

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