Dynamic expenses chart using JSON data file

I feel like my displayData() function is a bit out of control. This function is what makes the chart dynamic based on the data file. It receives the parsed data and then uses it to set the column heights, label the days, set the amounts for the column labels etc (and as I'm typing this I'm realizing that I could split all those up). I think I was unsure because the data came in all in the one JSON array.

Ideas on how to handle those separate tasks but also when reading from the one source of data?