JS实现当前页居中分页效果的方法

function show_page(cur_pc){  var cp=cur_pc;  //curent page count  var tp=this.p;  //total page count  var sp=this.pc;  //show page count  var bp;      //begin page count  var ep;      //end page count  if(sp%2==0) sp=sp+1;   //this process need an odd number  var dp=Math.floor(sp/2); //each side count to show  var dif=tp-sp;  //check weather it have enough page to make mid-show  var f=cp-dp;   //to check weather it has enough page to make mid-show from the begin  var g=tp-(cp+dp); //to check weather it has enough page to make mid-show from the end  if(sp && dif>=0)  {    if(g>0)    {      if(f>0)      {         bp=f;         ep=cp+dp;       }      else      {         bp=1;         ep=2*dp+1;       }    }    else    {       bp=tp-2*dp;       ep=tp;     }    }  else  {     bp=1;     ep=tp;   }  var buf=[];  for(var i=bp;i<=ep;i++)  {    if(i==cur_pc)    {      buf.push("<a href='javascript:;' class='current'>",i,"</a>");    }    else    {      buf.push("<a href='javascript:;' class='normal'>",i,"</a>");    }  }  document.write(buf);}