javascript分页代码(当前页码居中)

function setPage(opt){
if(!opt.pageDivId || opt.allPageNum < opt.curpageNum || opt.allPageNum < opt.showPageNum){return false};
var allPageNum = opt.allPageNum; //总的页数
var showPageNum = opt.showPageNum; //显示的页数
var curpageNum = opt.curpageNum; // 当前的页数
var pageDIvBox = document.getElementById(opt.pageDivId);
//左边或右边显示页码的个数
var lrNum = Math.floor(showPageNum/2);
if(curpageNum>1){
var oA = document.createElement('a');
oA.href='#1';
oA.innerHTML = '首页'
pageDIvBox.appendChild(oA);
}
if(curpageNum>1){
var oA = document.createElement('a');
oA.href='#'+(curpageNum-1);
oA.innerHTML = '上一页'
pageDIvBox.appendChild(oA);
}
if(curpageNum<showPageNum-2 || allPageNum == showPageNum){
for(var i=1;i<=showPageNum;i++){
var oA = document.createElement('a');
oA.href = '#'+i;
if(curpageNum==i){
oA.innerHTML = i;
}else{
oA.innerHTML = "[" + i + "]";
}
pageDIvBox.appendChild(oA);
}
}else{
//倒数第一页的处理
if(allPageNum-curpageNum<lrNum && curpageNum == allPageNum-1){
for(var i=1;i<=showPageNum;i++){
console.log((curpageNum - showPageNum + i));
var oA = document.createElement('a');
oA.href = '#'+ (curpageNum - (showPageNum-1) + i);
if(curpageNum == (curpageNum - (showPageNum-1) + i)){
oA.innerHTML = (curpageNum - (showPageNum-1) + i)
}else{
oA.innerHTML = '['+(curpageNum - (showPageNum-1) + i)+']'
}
pageDIvBox.appendChild(oA);
}
}
//最后一页的处理
else if(allPageNum-curpageNum<lrNum && curpageNum == allPageNum){
for(var i=1;i<=showPageNum;i++){
console.log((curpageNum - showPageNum + i));
var oA = document.createElement('a');
oA.href = '#'+ (curpageNum - showPageNum + i);
if(curpageNum == (curpageNum - showPageNum + i)){
oA.innerHTML = (curpageNum - showPageNum + i)
}else{
oA.innerHTML = '['+(curpageNum-showPageNum + i)+']'
}
pageDIvBox.appendChild(oA);
}
}else{
for(var i=1;i<=showPageNum;i++){
var oA = document.createElement('a');
oA.href = '#'+ (curpageNum - (showPageNum-lrNum) + i);
if(curpageNum == (curpageNum - (showPageNum-lrNum) + i)){
oA.innerHTML = (curpageNum - (showPageNum-lrNum) + i)
}else{
oA.innerHTML = '['+(curpageNum - (showPageNum-lrNum) + i)+']'
}
pageDIvBox.appendChild(oA);
}
}
}
if(curpageNum<allPageNum){
for(var i=1;i<=2;i++){
if(i==1){
var oA = document.createElement('a');
oA.href='#'+(parseInt(curpageNum)+1);
oA.innerHTML = '下一页'
}else{
var oA = document.createElement('a');
oA.href='#'+allPageNum;
oA.innerHTML = '尾页'
}
pageDIvBox.appendChild(oA);
}
}
var oA = document.getElementsByTagName('a');
//给页码添加点击事件
for(var i=0;i<oA.length;i++){
oA[i].onclick = function(){
//当前点的页码
var sHref = this.getAttribute('href').substring(1);
//清空页数显示
pageDIvBox.innerHTML = '';
setPage({
pageDivId:'page',
showPageNum:5, //显示的个数
allPageNum:10, //总页数
curpageNum:sHref //当前页数
})
}
}
}
window.onload = function(){
setPage({
pageDivId:'page',
showPageNum:5, //显示的个数
allPageNum:10, //总页数
curpageNum:1 //当前页数
})
}

昨天看了妙味课堂的 分页视频教程，今天自己参照其思路，自己写了下，并且自己新增了一个‘显示页码个数'的属性 ‘showPageNum';
下面对关键的几个地方做个总结：

1.点击的当前页码需要在显示的页码中居中;
无论是显示 3页 5页 7页 9页…… 等等
当前页要居中，可以推出一个公式
用显的页码个数除以2 再取整，就可以得到左右需要显的页码个数。这个对后面的分页判断很有用
var lrNum = Math.floor(showPageNum/2);
2.获取页码
this.getAttribute('href') 用它可以得到相对路径;this.href 用它只能得到绝对路径