/*
 **************************
 author:keel (keel.sike@gmail.com)
 **************************

 页码显示jquery插件,只需要存在#pagenav,则会在其中显示页码.
 调用时可根据需要先重写go方法.(已去除jquery依赖)

 **************************
 示例(注意：页面中放置id为pagenav的html对象):

 //转到页码时触发的自定义方法,p为当前页码,pn为总页数
 pagenav.fn = function(p,pn){
 alert(p+","+pn);
 };
 //初始跳到第3页,共33页
 pagenav.go(3,33);

 */
var pagenav = pagenav || {};
pagenav.fn = null;
//p为当前页码,pn为总页数
pagenav.nav = function(p, pn) {
    //只有一页,直接显示1
    if (pn <= 1) {
        this.p = 1;
        this.pn = 1;
        return this.phtml2(1);
    }
    if (pn < p) {
        p = pn;
    };
    var re = "";
    //第一页
    if (p <= 1) {
        p = 1;
    } else {
        //非第一页
        re += this.phtml(p - 1, pn, "上一页");
        //总是显示第一页页码
        re += this.phtml(1, pn, "1");
    }
    //校正页码
    this.p = p;
    this.pn = pn;

    //开始页码
    var start = 2;
    var end = (pn < 9) ? pn: 9;
    //是否显示前置省略号,即大于10的开始页码
    if (p >= 7) {
        re += "...";
        start = p - 4;
        var e = p + 4;
        end = (pn < e) ? pn: e;
    }
    for (var i = start; i < p; i++) {
        re += this.phtml(i, pn);
    };
    re += this.phtml2(p);
    for (var i = p + 1; i <= end; i++) {
        re += this.phtml(i, pn);
    };
    if (end < pn) {
        re += "...";
        //显示最后一页页码,如不需要则去掉下面这一句
        re += this.phtml(pn, pn);
    };
    if (p < pn) {
        re += this.phtml(p + 1, pn, "下一页");
    };
    return re;
};
//显示非当前页
pagenav.phtml = function(pageno, pn, showpageno) {
    showpageno = showpageno || pageno;
    var h = " <a href='javascript:pagenav.go(" + pageno + "," + pn + ");' class='pagenum'>" + showpageno + "</a> ";
    return h;

};
//显示当前页
pagenav.phtml2 = function(pageno) {
    var h = " <span class='cpagenum'>" + pageno + "</span> ";
    return h;
};
//输出页码,可根据需要重写此方法
pagenav.go = function(p, pn) {
    //$("#pagenav").html(this.nav(p,pn)); //如果使用jquery可用此句
    document.getelementbyid("pagenav").innerhtml = this.nav(p, pn);
    if (this.fn != null) {
        this.fn(this.p, this.pn);
    };
};