Collecting blocks - Create Combos?

Hello everyone,

The best way for me to explain the problem I am having is to take an example from another game. That game being AudioSurf.

In Audiosurf, you attempt to collect different colour blocks, and make combos with them. I have a similar type of combo collection that works the same way. You collect colours, and a combo is made with > 2 blocks beside/above/below each other. I need a efficient way to code combo detection, and then once the combo is detected, delete the blocks, and have any blocks that could have been above the deleted blocks, fall down to available positions.

For an example of this, please take a quick look at this video of Audiosurf, as it pretty much sums up what I need done.

I have already got the collection part working and everything, I just need a way to detect combos, and have certain blocks fall down if a block below them gets removed. Also, I am using javascript, but any help is appreciated of course!

I am not asking for someone to do this for me, just simply asking for clarification on how I would go about doing something like this.

Thanks a bunch,

-Kyle