<script type="text/JavaScript">

var size = 1.0;  
function showheight() {
    alert(document.body.clientHeight);
}
function zoomout() {
 size = size + 0.1;  
 set(); 
}  


function zoomin() {  
 size = size - 0.1;  
 set();  
}  


function set() {  
 //document.body.style.cssText = document.body.style.cssText + ‘; -webkit-transform: scale(‘ + size + ‘);-webkit-transform-origin: 0 0;‘;   
 //document.body.style.cssText = document.body.style.cssText + ‘; -webkit-transform: scale(‘ + size + ‘); ‘; 
 //$(body).css("width","120%);
document.body.style.zoom = size;
document.body.style.cssText += ‘; -moz-transform: scale(‘ + size + ‘);-moz-transform-origin: 0 0; ‘;     //
} 
    </script>
    <input type="button" onclick="javascript:zoomin();" value="http://www.mamicode.com/zoomin">
    <input type="button" onclick="javascript:zoomout();" value="http://www.mamicode.com/zoomout">
    <input type="button" onclick="javascript:showheight();" value="http://www.mamicode.com/showheight">