var c = document.getElementById("container");
function drag(o){
var left,top,x,y,flag;
o.onmousedown = function(e){
x = e.clientX;
y = e.clientY;
left = parseInt(getComputedStyle(o,null).left);
top = parseInt(getComputedStyle(o,null).top);
flag = true;
}
document.onmouseup = function(){
flag = false;
}
document.onmousemove = function(e){
if(flag){
var tx = e.clientX;
var ty = e.clientY;
o.style.left = left + tx -x + 'px';
o.style.top = top + ty - y + 'px';
console.log(tx,ty);
}
}
}
drag(c);
