Does a script need to be a child of a button for connect(function) to work?

This works fine:

button = script.parent

function click()
    print("hello")
end

button.MouseButton1Click:connect(click)

but this doesn't work?

function click()
    print("hello")
end

game.StarterGui.ScreenGui.TextButton.MouseButton1Click:connect(click)

This doesn't work too...

game.StarterGui.ScreenGui.TextButton.MouseButton1Click:connect(function (click)
    print("hello")
end)

in examples 2 and 3 script was not a child of the button TY