In JavaScript’s syntax, if $left and $top are not defined as variables, then {$left: '10px', $top: '10px'} is equivalent to {'$left': '10px', '$top':

In JavaScript’s syntax, if $left and $top are not defined as variables, then {$left: '10px', $top: '10px'} is equivalent to {'$left': '10px', '$top': '10px'} The library doesn’t have to define global variables for that code to work. So it probably doesn’t define them as global variables.