[removed] Remove duplicates of objects sharing same property value

Question

I have an array of objects that I would like to trim down based on a specific key:value pair. I want to create an array that includes only one object per this s

Answer 1

Off the top of my head there is no one function that will do this for you as you are dealing with an array of objects and also there is no rule for which duplicate would be removed as duplicate.

In your example you remove the one with size: small but if you were to implement this using a loop you'd most likely include the first and exclude the last as you loop through your array.

It may very well be worth taking a look at a library such as lodash and creating a function that uses a combination of it's API methods to get the desired behaviour you want.

Here is a possible solution you could use making use of basic Arrays and a filter expression to check whether a new item would be considered a duplicate before being attached to a return result.

var arrayWithDuplicates = [
    {"color":"red", "size": "small"},
    {"color":"green", "size": "small"},
    {"color":"blue", "size": "medium"},
    {"color":"red", "size": "large"}
];

var reduce = function(arr, prop) {
  var result = [],
      filterVal,
      filters,
      filterByVal = function(n) {
          if (n[prop] === filterVal) return true;
      };
  for (var i = 0; i < arr.length; i++) {
      filterVal = arr[i][prop];
      filters   = result.filter(filterByVal);
      if (filters.length === 0) result.push(arr[i]);
  }
  return result;
};

console.info(reduce(arrayWithDuplicates, 'color'));

You can check out some literature on Array filtering here If you need to provide a preference on which item to remove you could define extra parameters and logic that will make extra property checks before adding to a return value.

Hope that helps!