Hover window follow mouse, while respecting bounds of a given container

follow-mouse.js

function followMouse(e, $hover_window, $hover_bounder){
  var xOffset = e.pageX
    , yOffset = e.pageY
    , xBuffer = 10
    , yBuffer = 50

    , hover_window_height = $hover_window.outerHeight()
    , hover_window_width = $hover_window.outerWidth()

    , map_canvas_height = $hover_bounder.outerHeight()
    , map_canvas_width = $hover_bounder.outerWidth()

    , map_canvas_offset_left = $hover_bounder.offset().left
    , map_canvas_offset_top = $hover_bounder.offset().top;

    $hover_window.css({
      'top': yOffset + yBuffer,
      'left': xOffset - hover_window_width/2
    });

    // If it goes against the left wall
    if (xOffset < map_canvas_offset_left  + hover_window_width/2 + xBuffer){
      $hover_window.css({
        'left': xBuffer
      });
    };
    // If it goes against the right wall
    if(xOffset > map_canvas_width - hover_window_width/2 - xBuffer){
      $hover_window.css({
        'left': map_canvas_width - hover_window_width - xBuffer
      });
    };
    // If it goes against the bottom
    if(yOffset > map_canvas_height - hover_window_height - yBuffer){
      $hover_window.css({
        'top': yOffset - yBuffer/2 - hover_window_height
      });
    };
};

main.js

$('#hover_bounder').mousemove( function(e){
  followMouse(e, $hover_window, $(this));
});