原生javascript实现的分页插件pagenav

/*
 **************************
 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) "...";
    start = p - 4;
    var e = p + 4;
    end = (pn < e) "...";
    //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);
  };
};