.on('hover', function)与.hover(function, function)不同-它不接受两个函数.删除第二个事件，然后触发事件.

.on('hover', function) is not like .hover(function, function) - it doesn't accept two functions. Remove the second one and the events trigger.

http://jsfiddle.net/U78RV/4/

您仍然可以创建这两个事件

You can still create those two events

$("#firstBox").randomLetterStyles({type: 'mouseover', ...}).randomLetterStyles({type: 'mouseout', ...});