[] referencing

I’m doing some work which involves square grids.
I’ve used sprites to display the individual squares.
Now my question is how can i refer to the sprites like we used to refer to movieclips in AS2 like following?
this[‘block_’+j]For time beging, i’m just pushing all the square boxed into an array to refer them by array index.

getChildByName('block_'+j)

Thank you Felixz