直接引入下面的代码：

// 屏幕适配
!function(win) {
function resize() {
var domWidth = domEle.getBoundingClientRect().width;
if(domWidth / v > 540){
domWidth = 540 * v;
}
win.rem = domWidth / 37.5; // 2倍屏
domEle.style.fontSize = win.rem + “px”;
}
var v, initial_scale, timeCode, dom = win.document, domEle = dom.documentElement, viewport = dom.querySelector(‘meta[name=“viewport”]’), flexible = dom.querySelector(‘meta[name=“flexible”]’);
if (viewport) {
//viewport：<meta name=“viewport"content=“initial-scale=0.5, minimum-scale=0.5, maximum-scale=0.5,user-scalable=no,minimal-ui”/>
var o = viewport.getAttribute(“content”).match(/initial-scale=([”’]?)([\d.]+)\1?/);
if(o){
initial_scale = parseFloat(o[2]);
v = parseInt(1 / initial_scale);
}
} else {
if (flexible) {
var o = flexible.getAttribute(“content”).match(/initial-dpr=(["’]?)([\d.]+)\1?/);
if(o){
v = parseFloat(o[2]);
initial_scale = parseFloat((1 / v).toFixed(2))
}
}
}
if (!v && !initial_scale) {
var n = (win.navigator.appVersion.match(/android/gi), win.navigator.appVersion.match(/iphone/gi));
v = win.devicePixelRatio;
v = n ? v >= 3 ? 3 : v >= 2 ? 2 : 1 : 1, initial_scale = 1 / v
}
//没有viewport标签的情况下
if (domEle.setAttribute(“data-dpr”, v), !viewport) {
if (viewport = dom.createElement(“meta”), viewport.setAttribute(“name”, “viewport”), viewport.setAttribute(“content”, “initial-scale=” + initial_scale + “, maximum-scale=” + initial_scale + “, minimum-scale=” + initial_scale + “, user-scalable=no”), domEle.firstElementChild) {
domEle.firstElementChild.appendChild(viewport)
} else {
var m = dom.createElement(“div”);
m.appendChild(viewport), dom.write(m.innerHTML)
}
}
win.dpr = v;
win.addEventListener(“resize”, function() {
clearTimeout(timeCode), timeCode = setTimeout(resize, 300)
}, false);
win.addEventListener(“pageshow”, function(b) {
b.persisted && (clearTimeout(timeCode), timeCode = setTimeout(resize, 300))
}, false);

resize();

}(window);