Today I Learned

TIL, 2020-04-20

What is the difference between window, screen, and document in Javascript?


  • Window is the main JS object root, and can also be treated as the root of the DOM.
  • window.screen or just screen is a small information object about physical screen dimensions. The physical display’s full screen.
  • window.document or document is the main object of the visible document object/model/DOM.
  • Each browser tab has its own top-level window object, and each iframe has its own window too, nested within a parent window. window.window always refers to window, but window.parent and might refer to enclosing windows. window also has:
    • setTimeout and setInterval, binding event handlers to a timer.
    • location giving the current URL.
    • history with back() and forward().
    • navigator describing the browser software
  • document: Each window has a document object to be rendered. Then you can access stuff with document.body.something.
  • The document is your document that gets loaded into the browser.

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