javascript 简单问题


1. .ready是里面传了一个function() 是什么意思
2. .Draggable  是什么意思
3. zIndex:20 ,ghosting: false, opacity:0.7, handle:#layer_handle 这些参数都是什么 请解释一下,就是不懂语法而已不是很深滴.....
$(document).ready(function()
        {
            
            $('#layer').Draggable(
                    {
                        zIndex:     20,
                        ghosting:    false,
                        opacity:     0.7,
                        handle:    '#layer_handle'
                    }
                );