移动端flex自适应方案。（px to rem）

 define(function (require, exports, module) {
     exports.mobileUtilMethod = function () {
         (function (e, t) {
             function n() {
                 for (var e = navigator.userAgent,
                     t = ["Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod"], n = !0, i = 0; t.length > i; i++) if (e.indexOf(t[i]) > 0) {
                         n = !1;
                         break
                     }
                 return n
             }
             function i() {
                 var t = a.getBoundingClientRect().width;
                 n() && 2047 > t && (t = 640);
                 var i = t * 100 / w;
                 a.style.fontSize = i + "px",
                     d.rem = e.rem = i
             }
             var r, o = e.document,
                 a = o.documentElement,
                 s = o.querySelector('meta[name="viewport"]'),
                 c = o.querySelector('meta[name="flexible"]'),
                 l = 0,
                 u = 0,
                 d = t.flexible || (t.flexible = {});
             var w = o.querySelector('meta[name="W_design"]') ? o.querySelector('meta[name="W_design"]').getAttribute('content') : 640;
             if (s) {
                 // console.warn("将根据已有的meta标签来设置缩放比例");
                 var p = s.getAttribute("content").match(/initial\-scale=([\d\.]+)/);
                 p && (u = parseFloat(p[1]), l = parseInt(1 / u))
             } else if (c) {
                 var f = c.getAttribute("content");
                 if (f) {
                     var h = f.match(/initial\-dpr=([\d\.]+)/),
                         m = f.match(/maximum\-dpr=([\d\.]+)/);
                     h && (l = parseFloat(h[1]), u = parseFloat((1 / l).toFixed(2))),
                         m && (l = parseFloat(m[1]), u = parseFloat((1 / l).toFixed(2)))
                 }
             }
             if (!l && !u) {
                 e.navigator.appVersion.match(/android/gi);
                 var g = e.navigator.appVersion.match(/iphone/gi);
                 e.navigator.appVersion.match(/ipad/gi);
                 var v = e.devicePixelRatio;
                 l = g ? v >= 3 && (!l || l >= 3) ? 3 : v >= 2 && (!l || l >= 2) ? 2 : 1 : 1,
                     u = 1 / l
             }
             if (a.setAttribute("data-dpr", l), !s) if (s = o.createElement("meta"), s.setAttribute("name", "viewport"), s.setAttribute("content", "initial-scale=" + u + ", maximum-scale=" + u + ", minimum-scale=" + u + ", user-scalable=no"), a.firstElementChild) a.firstElementChild.appendChild(s);
             else {
                 var y = o.createElement("div");
                 y.appendChild(s),
                     o.write(y.innerHTML)
             }
             e.addEventListener("resize",
                 function () {
                     clearTimeout(r),
                         r = setTimeout(i, 300)
                 }, !1),
                 e.addEventListener("pageshow",
                     function (e) {
                         e.persisted && (clearTimeout(r), r = setTimeout(i, 300))
                     }, !1),
                 "complete" === o.readyState ? o.body.style.fontSize = 12 * l + "px" : o.addEventListener("DOMContentLoaded",
                     function () {
                         o.body.style.fontSize = 12 * l + "px"
                     }, !1),
                 i(),
                 d.dpr = e.dpr = l,
                 d.refreshRem = i,
                 d.rem2px = function (e) {
                     var t = parseFloat(e) * this.rem;
                     return "string" == typeof e && e.match(/rem$/) && (t += "px"),
                         t
                 },
                 d.px2rem = function (e) {
                     var t = parseFloat(e) / this.rem;
                     return "string" == typeof e && e.match(/px$/) && (t += "rem"),
                         t
                 }
         })(window, window.lib || (window.lib = {}));
     }
 })