Senior Node.js and JavaScript-programmer for an existing project

I have a Google Maps based web application (https://stormwindow.stormchasingusa.com) built with Node.js backend and (vanilla) JavaScript frontend, for which I need help from an experienced Node.js and JavaScript programmer. The project started off as a project to learn to code Node.js/JavaScript but has evolved into a real application and I lack the time to continue.

I need help with:
- Creating new features - this is about 60% of the job
- Refactoring the code to improve performance and raise the overall quality
- Fix bugs

You must be experienced with:
- Node.js (website is built with Express)
- JavaScript
- CSS/HTML
- Firestore (Google Cloud Platform) - quite basic stuff though
- Google Maps API
- git

I have created all the code myself and will be able to give good and detailed instructions and explain the existing code if necessary.