用JTrackBar实现的模拟苹果风格的滚动条_下拉菜单

function JObj(){}
JObj.$c = function(tag){return document.createElement(tag)};
JObj.$ = function(id){return document.getElementById(id)};
JObj.isRate = function(pRateString){
if(!isNaN(pRateString)) return false;
if(pRateString.substr(pRateString.length-1,1) != "%")
return false;
if(isNaN(pRateString.substring(0,pRateString.length - 1)))
return false;
return true;
}

function JPos(){}
JPos.getAbsPos = function(pTarget){
var x_ = y_ = 0;
while(pTarget.offsetParent){
x_ += pTarget.offsetLeft;
y_ += pTarget.offsetTop;
pTarget = pTarget.offsetParent;
}
x_ += pTarget.offsetLeft;
y_ += pTarget.offsetTop;
return {x:x_,y:y_};
}

JPos.getMousePos = function(evt){
var x_ = y_ = 0;
evt = evt || window.event;
if(evt.pageX || evt.pageY){
x_ = evt.pageX;
y_ = evt.pageY;
}else{
x_ = evt.clientX + document.body.scrollLeft - document.body.clientLeft;
y_ = evt.clientY + document.body.scrollTop - document.body.clientTop;
}

return {x:x_,y:y_};
}