How To Fetch Text From a File and Put it in Quilljs?

Hello, I'm trying to program a simple wordprocessor with Quilljs, and right now I'm running into issues with trying to load text from files and input them into the quilljs editor.

Quilljs has this function:
quill.setText(text: string, source: string = 'api'): Delta

And I want to use either javascript or html to open a filepicker, open a file, and fetch the text from that file and send it to that function. How would I do that?