Need help with a program that I am currently writing

Hello Glitch Community,
I am a Python newb and an even bigger Javascript newb. I made an app using Python Libraries to take an Excel File(.xls or .xlsx), convert it into a CSV file, and then email that CSV file to the desired email using Yagmail. To grab the wanted Excel file, I am using to let the user choose the file. Here is where I come into an issue. I am not able to get the file path of the Excel file by using <input type="file> and I need the file path to convert the Excel file to a CSV file so I can attach the CSV into the Email. So, what I am asking is for advice on how to do this.
Thanks for the help in advance,
Aryan Kini