普通Html 页面 rem适配

核心代码：

		;(function(win, doc) {
		    'use strict';
		    var options = { width: 750, dpr: win.devicePixelRatio };
		    var html = doc.documentElement,
		        width = html.getAttribute('data-width') || options.width,
		        dpr = html.getAttribute('data-dpr') || options.dpr,
		        viewPort = doc.querySelector('meta[name="viewport"]'),
		        rotate = win.onorientationchange ? 'orientationchange' : 'resize';
		
		    // 设置html fontSize
		    function setSize() {
		        var winWidth = win.innerWidth || html.clientWidth;
		        html.style.fontSize = 100 * winWidth / width + 'px';
		    };
		
		    // 设置 initial-scale
		    function setScale() {
		        setSize();
		        var viewContent = viewPort.getAttribute('content');
		        var reg = /initial-scale=(\d(.\d+)?)/i;
		        var matchRes = viewContent.match(reg);
		        var scale = 1 / parseInt(dpr);
		        if (matchRes && matchRes[1] == scale) {
		            return;
		        }
		        var newContent = viewContent.replace(reg, function(a, b) {
		            return a.replace(/\d(.\d+)?/i, scale);
		        });
		        viewPort.setAttribute('content', newContent);
		    };
		    
		    win.addEventListener(rotate, setSize);
		    window.requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame;
		    requestAnimationFrame(setScale);
		}(window, document));