I am learning JavaScript and I am using Atom (Text Editor). On my HTML file I got only this:

    
    


    
Hello Plunker!
    Display Todos
    Toggle Todos

On my javascript file, I am simply trying to access the "Display todos" button using this:

var displayTodosButton = document.getElementById('displayTodosButton')

I was watching a video, and the instructor is using plnkr.co, and he accesses the button just fine, yet on Atom I get the "ReferenceError: document is not defined"

How can I fix this?