表格拖动效果js

window.onload=function(){
drag(document.getElementById('drag1'));
drag(document.getElementById('drag2'));
drag(document.getElementById('drag3'));
drag(document.getElementById('drag4'));
};
function drag(o,r)
{
/*取得o.parentNode.parentNode.cells的宽度，兼容IE6和Firefox*/
o.p_p_c_gw=function(index)
{
if(window.ActiveXObject)
{
return o.parentNode.parentNode.cells[o.parentNode.cellIndex+index].offsetWidth;
}
else
{
return parseInt(o.parentNode.parentNode.cells[o.parentNode.cellIndex+index].offsetWidth)-
parseInt(o.parentNode.parentNode.parentNode.parentNode.cellPadding)*2-2;
}
}
/*设置所有行的第index个单元格为w，在IE下可只设第一行*/
o.p_p_p_sw=function(index,w)
{
for(var i=0;i<o.parentNode.parentNode.parentNode.parentNode.rows.length;i++)
{
o.parentNode.parentNode.parentNode.parentNode.rows[i].cells[index].style.width=w;
}
}

//var out=document.getElementById('my');
o.firstChild.onmousedown=function(){return false;};
o.onmousedown=function(a)
{
var d=document;
if(!a)
a=window.event;
var lastX=a.clientX;
//有时候拖拽过快表格会变大，至于为什么会这样我也不清楚。watch_dog是为了保证表格不会变大，
var watch_dog=o.p_p_c_gw(0)+o.p_p_c_gw(1);
if(o.setCapture)
o.setCapture();
else if(window.captureEvents)
window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP); 
d.onmousemove=function(a)
{
if(!a)
a=window.event;
if(o.p_p_c_gw(0)+o.p_p_c_gw(1)>watch_dog)
{
o.p_p_p_sw(o.parentNode.cellIndex+1,watch_dog-o.p_p_c_gw(0));
return;
}
var t=a.clientX-lastX;
//out.innerHTML=t;
if(t>0)
{
//right
if(parseInt(o.parentNode.parentNode.cells[o.parentNode.cellIndex+1].style.width)-t<10)
return;
o.p_p_p_sw(o.parentNode.cellIndex,o.p_p_c_gw(0)+t);
o.p_p_p_sw(o.parentNode.cellIndex+1,o.p_p_c_gw(1)-t);
}
else
{
//left
if(parseInt(o.parentNode.parentNode.cells[o.parentNode.cellIndex].style.width)+t<10)
return;
o.p_p_p_sw(o.parentNode.cellIndex,o.p_p_c_gw(0)+t);
o.p_p_p_sw(o.parentNode.cellIndex+1,o.p_p_c_gw(1)-t);
  }
  lastX=a.clientX;
  };
  d.onmouseup=function()
  {
if(o.releaseCapture)
o.releaseCapture();
else if(window.captureEvents)
window.captureEvents(Event.MOUSEMOVE|Event.MOUSEUP);
d.onmousemove=null;
d.onmouseup=null;
   };
};
}