关于移动端meta标签和JS兼容适配

<meta http-equiv="Pragma" content="no-cache">

<meta http-equiv="Cache-Control" content="no-cache">

<meta http-equiv="Expires" content="0">

<meta name="format-detection" content="telephone=no" />

<meta name="apple-mobile-web-app-capable" content="yes" />

<meta name="apple-mobile-web-app-status-bar-style" content="black" />

<meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0,user-scalable=no">

<!--移动端兼容适配 --> 

<script> 

// class 

! function( navigator ) { 

var userAgent = navigator.userAgent; 

documentElement = document.documentElement; 

if ( userAgent.match( /micromessenger\/5/gi ) ) { 

documentElement.className += " mobile wx_mobile wx_mobile_5"; 

} else if ( userAgent.match( /micromessenger/gi ) ) { 

documentElement.className += " mobile wx_mobile"; 

} else if ( userAgent.match( /ucbrowser/gi ) ) { 

documentElement.className += " mobile uc_mobile"; 

} else if ( /android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test( userAgent.toLowerCase() ) ) { 

documentElement.className += " mobile"; 

} else if ( userAgent.toLowerCase().match( /msie/gi ) && ( parseFloat( userAgent.toLowerCase().match( /msie ([0-9]{1,}[\.0-9]{0,})/i )[1] || 999 ) < 9 ) ) { 

documentElement.className += " pc pc-ie pc-ie8"; 

} else if ( userAgent.toLowerCase().match( /msie/gi ) || navigator.msPointerEnabled || navigator.pointerEnabled ) { 

documentElement.className += " pc pc-ie"; 

} else { 

documentElement.className += " pc";  

} 

}( navigator ); 

// meta 

! function( userAgent ) { 

var screen_w = parseInt(window.screen.width), 

scale = screen_w / 640; 

if ( /Android (\d+\.\d+)/.test( userAgent ) ) { 

var version = parseFloat( RegExp.$1 ); 

document.write( version > 2.3 

? '<meta name="viewport" content="width=640, minimum-scale = ' + scale + ", maximum-scale = " + scale + ', target-densitydpi=device-dpi">' 

: '<meta name="viewport" content="width=640, target-densitydpi=device-dpi">' ); 

} else { 

document.write( '<meta name="viewport" content="width=640, user-scalable=no, target-densitydpi=device-dpi">' ); 

} 

}( navigator.userAgent ); 

</script> 

<!--移动端兼容适配 end -->