Overwhelmed on my first job

Hello everyone!

I just landed my first Front-End Developer job at a company that makes software for people who are investing. The software provides information about stocks, and shows people how they can change their portfolios to make them better on different ways, shows graphs on different situations.

The problem is, this is my first job on the field. I'm mostly self taught, with 6 months of a bootcamp and started yesterday and am now worried about how I'm going to perform. I am used to and think I'm pretty good at working on my own projects, but had never worked on something with an existing base.

The code base is very large, with so many files and each component has around 1000 lines of code at the very least. Even finding the files that make a component work is hard since there is so much.

The only other Front-End Developer on my team, that I thought I'd be working with and be a Junior to, is leaving on Friday.

He gave me a task yesterday (one hour before leaving) to add an analyze feature to one of the pages. Today, I worked on it, I was able to get some results but was missing some part about updating something on local storage so it could graph on it.

I took a long time to get some results, but they weren't quite correct, and he finally just gave me the code to make it work. I will definitely try to get him on a call tomorrow so he can show me what he's working on, and try to get him to introduce me to more of the code.

I'm feeling very overwhelmed, don't know if I should start applying to a different job or just work hard to understand this codebase. I know it will take me time to become really productive.

What's your advice?