Function To Aggregate Rows in Javascript / Google Sheets

I'd like to create a function to aggregate rows from a javascript array. To aggregate the rows, I'd like to be able to match up to 3 columns, or more if possible and then sum another column. So in other words, if the row {Apple, Green, South America, $50} appears and then {Apple, Green, South America, $25} the function should aggregate those rows to {Apple, Green, South America, $75}. The function should take as inputs the array, the columns to match rows on, and the column to sum up. There should be able to be more columns than matching on or summing up. For instance, the array I'm trying to handle has about 12 columns, but I don't need to match on all elements. Then the function should export a new array with aggregated rows based on the above. The method should be able to work in Google Sheets / Google Script. The script here is sort of what I'm looking for but doesn't seem to quite work for what I'm trying to do. Its a similar goal though: [login to view URL]