视口大小、屏幕分辨率、鼠标位置

此代码与跨浏览器兼容，并检查视口、屏幕分辨率和鼠标位置的尺寸，这对于使用JavaScript执行一些检查非常有用。

<script type="text/javascript">
function getViewportWidth()
{
       if (window.innerWidth)
       {
               return window.innerWidth;
       }
       else if (document.body && document.body.offsetWidth)
       {
               return document.body.offsetWidth;
       }
       else
       {
               return 0;
       }
}

function getViewportHeight()
{
       if (window.innerHeight)
       {
               return window.innerHeight;
       }
       else if (document.body && document.body.offsetHeight)
       {
               return document.body.offsetHeight;
       }
       else
       {
               return 0;
       }
}

var tellMeTheSizes=function()
{
       document.getElementById("viewportwidth").innerHTML = getViewportWidth() + "px";
       document.getElementById("viewportheight").innerHTML = getViewportHeight() + "px";
       document.getElementById("resolutionheight").innerHTML = screen.height + "px";
       document.getElementById("resolutionwidth").innerHTML = screen.width + "px";
}

window.onload=function()
{
       tellMeTheSizes();
}

window.onresize=function()
{
       tellMeTheSizes();
}

window.onmousemove=function(event)
{
       ev = event || window.event;
       document.getElementById("mousetop").innerHTML = ev.pageY + "px";
       document.getElementById("mouseleft").innerHTML = ev.pageX + "px";
}
</script>