移动端H5自适应js

// 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 / 750;
                if (/Android (\d+\.\d+)/.test(userAgent)) {
                    var version = parseFloat(RegExp.$1);
                    document.write(version > 2.3 ? '<meta name="viewport" content="width=750, minimum-scale = ' + scale + ", maximum-scale = " + scale + ', target-densitydpi=device-dpi">' : '<meta name="viewport" content="width=750,target-densitydpi=device-dpi">');
                } else {
                    document.write('<meta name="viewport" content="width=750, user-scalable=no">');
                }
            }(navigator.userAgent);