// JavaScript Document
var zhang=2
function next()
{ 
	if(zhang==49)
		{ 
			alert("这已经是封底了!") 
			zhang=48 
		}
	if(zhang>49)
		{ 
			alert("这已经是封底了!") 
			zhang=48
		} 
	if(zhang==4 || zhang==5)
		{
			getnext(zhang)
			
		}
		else
			{
				document.getElementById("vir_divall").style.display = 'none'
				document.getElementById("divall").style.display = 'block'
				document.getElementById("tu").src="content/"+zhang+".jpg" 
				zhang++				
			}
} 

function jump(i)
{
	document.getElementById("vir_divall").style.display = 'none'
	document.getElementById("divall").style.display = 'block'
    document.getElementById("tu").src="content/"+i+".jpg"
	zhang=++i
} 
function getnext(i)
{
    zhang=i
	document.getElementById("vir_divall").innerHTML = "<iframe src=\"catalog/catalog"+i+".htm\" scrolling=\"no\" frameborder=\"0\" width=\"748\" height=\"1066\"></iframe>"
	document.getElementById("vir_divall").style.display = 'block'
	document.getElementById("divall").style.display = 'none'
	document.getElementById("tu").src="content/"+i+".jpg"
	zhang=i+1
}
function getpre(i)
{
var n
    zhang=i
	n=zhang-2
	document.getElementById("vir_divall").innerHTML = "<iframe src=\"catalog/catalog"+n+".htm\" scrolling=\"no\" frameborder=\"0\" width=\"748\" height=\"1066\"></iframe>"
	document.getElementById("vir_divall").style.display = 'block'
	document.getElementById("divall").style.display = 'none'
	document.getElementById("tu").src="content/"+i+".jpg"
	zhang=zhang-1
} 
function up()
{ 
var m
	if(zhang==2)
		{ 
			alert("这已经是封面了!") 
			zhang=3 
		}
		else
			if(zhang==6 || zhang==7)
				{   
					getpre(zhang)
				
				}
			else
				{
					m=zhang-2
					document.getElementById("vir_divall").style.display = 'none'
					document.getElementById("divall").style.display = 'block'
					document.getElementById("tu").src="content/"+m+".jpg" 
					zhang--
				}
}
function GetRandomNum(Min,Max){   
        var Range = Max - Min;   
        var Rand = Math.random();   
        return(Min + Math.round(Rand * Range));   
}