First Pull Request for HACKTOBERFEST

In the first week of Hacktoberfest, we are required to make a pull request to an open source project. The first pull request can be really easy like fixing the spelling or grammar of an open source project but because I cannot find any spelling or small mistakes, I searched through Github and found this amazing project about Algorithms in every language

I request an issue on C++ Factorial but while I am working on it, someone create a pull request on Factorial C++ so I have to do the Factorial on JavaScript instead of C++. The work is relatively simple since I am also study about Algorithms this term. This function takes me 10 minutes to complete. I have created the pull request but it is from JavaScript issue. The first pull request is quite messy but I am happy that i can contribute something to this project.