Introduction
1- In the style of your item (like img, div, etc...) make the position as absolute, for example:
<div style="position:absolute" id="move_id" onmousedown="mousedown()" onmouseup="mouseup()">
2- You should have a temp for describe the condition of your item. set the display as none to hide the temp. the value of this input describes the condition. The value 0 means that the item is not dragged. when your mouse is down over the item (onmousedown) this value will set by 1 to be ready for drag and move.
<input type="text" style="display:none" id="temp_id" value="0">
3- make the <body> like this:
<body onmousemove="mousemove();">
4- Now we can make the JavaScript functions:
<script language="javascript" type="text/javascript">
function mousedown()
{
document.getElementById("temp_id").value = "1";
}
function mouseup()
{
document.getElementById("temp_id").value = "0";
document.getElementById("move_id").style.cursor = "default";
}
function mousemove()
{
if (document.getElementById("temp_id").value == "1")
{
document.getElementById("move_id").style.top = event.clientY - 10;
document.getElementById("move_id").style.left = event.clientX - 50;
document.getElementById("move_id").style.cursor = "move";
}
}
</script>