移动设备页面自适应

;(function(){
var w = parseInt(window.screen.width),
s = w/640,
u = navigator.userAgent.toLowerCase(),
m = '<meta name="viewport" content="width=640,';
if (/android (\d+\.\d+)/.test(u)){
if(parseFloat(RegExp.$1)>2.3) m += 'minimum-scale='+s+',maximum-scale='+s+',';
}else{
m += 'user-scalable=no,';
}
m += 'target-densitydpi=device-dpi">';
document.write(m);
}());