So imagine you have an array with a bunch of values, and you want to remove all of the duplicate values. There are a lot of different ways to do this... I was trying to come up with a way to do this without creating a new array. I was thinking that Array,indexOf() is probably just a loop that runs though an array from 0 until the end. If this assumption was true, I could catch dupes by looping through backwards, and checking if indexOf is not equal to the current iteration. This way I have a loop running from length to 0, and a built in loop running from 0 to length. Turns out, I was right. Here's the code.
And a JSFiddle Demo!