Why isn't lodash's _.unique returning unique objects when I pluck a field that is an object?

Question

I'm using lodash's _.unique and it's not working as expected. I'm doing this:

uniqueByFocusIndex = _.unique(clickables, false, "focusIndex");

And as you can see in the image (look at the right), it's returning two elements with the same values for their focusIndexes. I'd expect this to return one of the two, not both. Is it because _.unique only works on primitives and not objects?

Click to expand:

Answer 1

_.uniqWith is what you might need so that you can do comparison using _.isEqual

_.uniqWith(clickables, _.isEqual)

It is suggested in the docs

Answer 2

It doesn't work because comparing objects is done by reference and returns false even if the objects' contents are the same.

Using a string for the callback will check those values using the pluck callback style, but comparison of those objects you have under that key will always be false.

I tried to find a way to do this with some other callback, but I think you would be better off just writing your own uniq function that fits your purposes.