Web移动端开发常见问题和方案

一、两种rem解决方案

1，根据dpi来设定rem以及viewport
（美团的REM解决方案）

//根据屏幕大小及dpi调整缩放和大小  
        (function() {  
            var scale = 1.0;  
            var ratio = 1;  
            if (window.devicePixelRatio >= 2) {  
                scale *= 0.5;  
                ratio *= 2;  
            }  
            var text = '<meta name="viewport" content="initial-scale=' + scale + ', maximum-scale=' + scale +', minimum-scale=' + scale + ', width=device-width, user-scalable=no" />';  
            document.write(text);  
            document.documentElement.style.fontSize = 50*ratio + "px";  
        })();  

2，根据屏幕宽度来设置rem

var autoChange=function(maxWidth,originSize){  
    var width=document.documentElement.clientWidth;  
    var Standard=originSize/(maxWidth*1.0/width);  
    Standard=Standard>100?100:Standard;  
    document.querySelector("html").style.fontSize=Standard+"px";  
};  
autoChange(750,100);  

3. 手机端页面自适应解决方案—rem布局进阶版
   https://www.jianshu.com/p/985d26b40199/

<script>!function(e){function t(a){if(i[a])return i[a].exports;var n=i[a]={exports:{},id:a,loaded:!1};return e[a].call(n.exports,n,n.exports,t),n.loaded=!0,n.exports}var i={};return t.m=e,t.c=i,t.p="",t(0)}([function(e,t){"use strict";Object.defineProperty(t,"__esModule",{value:!0});var i=window;t["default"]=i.flex=function(normal,e,t){var a=e||100,n=t||1,r=i.document,o=navigator.userAgent,d=o.match(/Android[\S\s]+AppleWebkit\/(\d{3})/i),l=o.match(/U3\/((\d+|\.){5,})/i),c=l&&parseInt(l[1].split(".").join(""),10)>=80,p=navigator.appVersion.match(/(iphone|ipad|ipod)/gi),s=i.devicePixelRatio||1;p||d&&d[1]>534||c||(s=1);var u=normal?1:1/s,m=r.querySelector('meta[name="viewport"]');m||(m=r.createElement("meta"),m.setAttribute("name","viewport"),r.head.appendChild(m)),m.setAttribute("content","width=device-width,user-scalable=no,initial-scale="+u+",maximum-scale="+u+",minimum-scale="+u),r.documentElement.style.fontSize=normal?"50px": a/2*s*n+"px"},e.exports=t["default"]}]);  flex(false,100, 1);</script>

二、移动端默认字体设置推荐

<style>  
body{ font-family: "Helvetica Neue",Helvetica,Arial,sans-serif;  }  
</style> 

三、简单的flexbox兼容方案

<style>  
/* 父级元素 */  
display: -webkit-box;  
display: -webkit-flex;  
display: flex;  
/* 子集元素 */  
-webkit-box-flex: 1;  
-webkit-flex: 1;  
flex: 1;  
</style> 

四、点透

（未完待续）