Typescript + Linters

Taking a small break from Telescope until the summer semester resumes. I've started collaborating with a elementary school friend on a project to build a clone of the game Adventure Capitalist. After working with Javascript for so long, I decided to try doing this in Typescript. It went pretty well up until I had the following line of code:

const index = this.shops.findIndex((shop: Shop) => shop.name == shopName);

When I was trying to compile my code, I kept getting the following error

Property 'findIndex' does not exist on type 'Shop[]' 

Pretty sure this should work as shops is an array of type Shop. As a developer usually does when they run into issues, I started googling the problem and checking Stack Overflow. It recommended I change my tsconfig.json "target" to es2015 and the findIndex() is an es6 function and add es6 to "lib". I did all that and tried compiling, still no good. I reached out to my frequent collaborator from Telescope @manekenpix and he suggested I just try running the code. It works?

Turns out it was a linter issue, although it still compiled properly. Upon further research 2 hours later, I realized I was using the cli command wrong, or at least the way I was using it was going to cause errors. I was compiling my .ts to .js by using the command tsc index.ts instead of tsc, when a specific file name is used, it will disregard the tsconfig.json file settings and just try to compile your Typescript to Javascript. So I tried running 'tsc', it worked! No errors and it was outputting all the compiled .js files inside my /build folder (ignored in .gitignore) I specified in my tsconfig.json file.