Keeping the last element in an array with the same property

Question

Let's imagine I have this array:

bucket.bucketList =[];

bucket.addItem = function(item) {
  bucket.bucketList.push(item);
}

The function pushes an object called foo this into the array on every mouse-scroll:

Some foo's also have a property , foo.name = "something";

The question is, what is the best way to delete All duplicates based on their name property names whilst keeping the most recents one pushed in?

I am using jQuery already in my project, so if jQuery has a more elegant way of doing this than vanilla JS i'd be more than happy to use it.

jfriend00 · Accepted Answer · 2014-05-13 05:22:05Z

2

This code removes all duplicate names, keeping the last one in the array.

You can traverse backwards through the array and remove any items with a name that you've already seen, using an object to keep track of the names you've already seen. By traversing backwards, you keep the last one and you don't have to do any array index corrections when you remove the current entry from the array:

var dict = {}, item;
for (var i = bucket.bucketList.length - 1; i >= 0 ; i--) {
    item = bucket.bucketList[i];
    if (item.name) {
        // if already in the dict, remove this array entry
        if (dict[item.name] === true) {
            bucket.bucketList.splice(i, 1);
        } else {
            // add it to the dict
            dict[item.name] = true;
        }
    }
}

edited May 13, 2014 at 5:22

answered May 13, 2014 at 5:16

jfriend00

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3 Comments

nicholaswmin Over a year ago

Are you iterating over the array backwards here?

jfriend00 Over a year ago

@NicholasKyriakides - yes, it's a backwards iteration for two reasons. 1) The OP wants to keep the last item of a dup so going backwards makes that easier because you see the last one first. 2) When you remove elements from the array with a backwards iteration, you don't have to correct your indexing like you do if you iterate forwards.

nicholaswmin Over a year ago

@Thanks, I am guilty of code copy-paste and now I am trying to rectify my mistake - I am the OP.

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