To try this out:
wget https://www.fec.gov/files/bulk-downloads/2018/indiv18.zip
unzip indiv18.zip
node find-most-frequent-name.js itcont.txt
The interesting thing is that while other solutions to the problem require to increase NodeJs' memory limits, we can even restrict the limit and use less memory:
node --max-old-space-size=300 find-most-frequent-name.js itcont.txt