Web Audio API (How to show EQ data of mp3 in array)

I would like to generate an array that holds EQ information about an mp3 using the analyser node http://ift.tt/1f5385N

The goal is to have a single digit representing the entire mp3's average amplitude of a specific range of frequencies. Ex) 100 Hz - 200 Hz should output a single digit, 5dB. The array will come into play because I will define 24 different EQ ranges up front, which i'd like to output 24 values.

Sooo, an array including 24 different values that represent the average amplitude of 24 specific ranges over time.

How can this be done using Javascript? thanks