jquery的fadein“slow”太快

$('#myItem').fadeOut(1500); // 1.5 seconds

$.fx.speeds.slow = 1500; // 'slow' now means 1.5 seconds
$.fx.speeds.xslow = 3000; // 'xslow' means 3 seconds
$.fx.speeds.xfast = 100; // 'xfast' means 0.1 seconds

$('#myItem').fadeOut('slow');
$('#myItem').fadeOut('xslow');
$('#myItem').fadeOut('xfast');

$('#myID').fadeIn(100, function() {
  // complete
});

http://api.jquery.com/fadeIn/

$('#someId').fadeIn(3000); // 3 second fade in

$('#Id').fadeIn(3500);