页面十字交叉定位

 

 

<script type="text/javascript">
        function mouseMove(event) {
            var event = window.event || event;
            var x_div = document.getElementById("x_div"),
         y_div = document.getElementById("y_div"),
         Mouse = document.getElementById("Mouse"),
         top = event.clientY > (window.screen.availHeight / 2) ? -30 : 10,
         left = event.clientX > (window.screen.availWidth / 2) ? -120 : 20;

            document.getElementById("XXX").innerHTML = event.clientX;
            document.getElementById("YYY").innerHTML = event.clientY;

            Mouse.style.top = event.clientY + top + "px";
            Mouse.style.left = event.clientX + left + "px";
            Mouse.style.display = "none";

            x_div.style.top = event.clientY - 10 + "px";
            y_div.style.left = event.clientX - 10 + "px";
            //y_div.style.height = document.body.scrollHeight;
        }
        function ss() {
            var txt = document.getElementById("help").value;
            var x_div = document.getElementById("x_div");
            var y_div = document.getElementById("y_div");
            if (txt == "帮助") {
                x_div.style.display = "block";
                y_div.style.display = "block";
                document.getElementById("help").value = "取消";
                document.onmousemove = mouseMove;
            }
            else {
                x_div.style.display = "none";
                y_div.style.display = "none";
                document.getElementById("help").value = "帮助";
                document.onmousemove = "";
            }

        }
    </script>

 <input id="help" onclick="ss();" type="button" value="帮助" />