移动端web页面自适应:rem的运用

!function(J, I) {

 function H() {
 var d = E.getBoundingClientRect().width;
 d / B > 540 && (d = 540 * B);
 var e = d / 10;
 E.style.fontSize = e + "px",
 z.rem = J.rem = e;
 }
 var G, F = J.document,
 E = F.documentElement,
 D = F.querySelector('meta[name="viewport"]'),
 C = F.querySelector('meta[name="flexible"]'),
 B = 0,
 A = 0,
 z = I.flexible || (I.flexible = {});
 if (D) {
 console.warn("将根据已有的meta标签来设置缩放比例");
 var y = D.getAttribute("content").match(/initial\-scale=([\d\.]+)/);
 y && (A = parseFloat(y[1]), B = parseInt(1 / A))
 } else {
 if (C) {
 var x = C.getAttribute("content");
 if (x) {
 var w = x.match(/initial\-dpr=([\d\.]+)/),
 v = x.match(/maximum\-dpr=([\d\.]+)/);
 w && (B = parseFloat(w[1]), A = parseFloat((1 / B).toFixed(2))),
 v && (B = parseFloat(v[1]), A = parseFloat((1 / B).toFixed(2)))
 }
 }
 }
 if (!B && !A) {
 var u = (J.navigator.appVersion.match(/android/gi), J.navigator.appVersion.match(/iphone/gi)),
 t = J.devicePixelRatio;
 B = u ? t >= 3 && (!B || B >= 3) ? 3 : t >= 2 && (!B || B >= 2) ? 2 : 1 : 1,
 A = 1 / B
 }
 if (E.setAttribute("data-dpr", B), !D) {
 if (D = F.createElement("meta"), D.setAttribute("name", "viewport"), D.setAttribute("content", "initial-scale=" + A + ", maximum-scale=" + A + ", minimum-scale=" + A + ", user-scalable=no"), E.firstElementChild) {
 E.firstElementChild.appendChild(D)
 } else {
 var s = F.createElement("p");
 s.appendChild(D),
 F.write(s.innerHTML)
 }
 }
 J.addEventListener("resize",
 function() {
 clearTimeout(G),
 G = setTimeout(H, 300)
 },
 !1),
 J.addEventListener("pageshow",
 function(b) {
 b.persisted && (clearTimeout(G), G = setTimeout(H, 300))
 },
 !1),
 "complete" === F.readyState ? F.body.style.fontSize = 12 * B + "px": F.addEventListener("DOMContentLoaded",
 function() {
 F.body.style.fontSize = 12 * B + "px"


 },
 !1),
 H(),
 z.dpr = J.dpr = B,
 z.refreshRem = H,
 z.rem2px = function(d) {
 var c = parseFloat(d) * this.rem;
 return "string" == typeof d && d.match(/rem$/) && (c += "px"),
 c
 },
 z.px2rem = function(d) {
 var c = parseFloat(d) / this.rem;
 return "string" == typeof d && d.match(/px$/) && (c += "rem"),
 c
 }
} (window, window.lib || (window.lib = {}));