Mortgage Repayment Calculator using Vanilla Javascript, HTML, CSS

What challenges did you encounter, and how did you overcome them?

Putting the input indicator such as the currency icon, years, and % into the input box was a bit challenging for me but i did it in probably not the most efficient way.

What specific areas of your project would you like help with?

I don't know how do you put commas in each number if it's a big number such as: 1000 into 1.000 or 500000 into 500.000

This would really help me if someone can tell me how, thanks :)