As a matter of security, web browsers don't let us directly change files that live in your computer's file system. Therefore you'll need to upload one or more files to the browser that you can use throughout this tutorial.
Within each challenge, you'll see that you can upload files from your computer either by dragging and dropping or selecting them from your file explorer. If you look closely at the run function in the code editor, you'll notice that it now takes an argument files. When you upload files from your computer, we'll make sure they're passed into the function as the files array. As long as you don't refresh your browser, these files will remain accessible for the next lesson in the tutorial, but you'll also have the option to upload different files to work with for each lesson.
To practice, let's upload one or more files from your computer and take a look at what's been received by the browser as the files array.
First, upload one or more files by dragging and dropping below or clicking to make a selection from your file explorer. Next, in the code editor, remove the comment markers (//) that precede return files within the run function.
Feeling stuck? We'd love to hear what's confusing so we can improve this lesson. Please share your questions and feedback.