There are a few sites that help you find projects to contribute to:
You still have time - Hacktoberfest
Search for GitHub projects that have an issue with the label up-for-grabs or jump-in
Other than that, think about npm packages (or nuget or anything else) that you often use, and check their repositories for information about how to contribute (in their readme.md or contributing.md files) or just check their issues.
Good luck!