Commands

node abn-amro.mjs <export.TAB> [--account <number>]                     # CSV to stdout
node abn-amro.mjs <export.TAB> [--account <number>] --append <file.csv> # add rows the file doesn't have

Download transactions in Internet Banking in the TXT format; the file is named TXT<timestamp>.TAB. An export can hold several accounts; --account picks one (the first column of the file).

--append matches rows on Date, Amount and Balance After, adds the new ones at the end, and leaves any extra columns of the file (your own Category, Note, …) empty for them. It creates the file if it doesn't exist. Rows in a description format it doesn't know get an empty Type and a warning.

Output

UTF-8, CRLF, oldest row first, dot decimals, signed amounts (negative = money out):