How to simply check if a file exists on the hard drive?

Is there a simple way to check if a file exists in a folder on the user's hard drive (standalone game) without having to create an array of all files in the folder and iterate through it?

You can use File.Exists:

Funny enough, the usage is identical in C# and JS

if (System.IO.File.Exists("myfile.txt"))
    //do stuff