html动态设置font-size

<script>
		//font-size,窗口自适应
		(function (doc, win) {
			var dpr, rem, scale;
			var docEl = document.documentElement;
			var metaEl = document.querySelector('meta[name="viewport"]');
			var resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
			if (navigator.userAgent.match(/(Android)/)) {
				dpr = 1;
			} else {
				dpr = win.devicePixelRatio || 1;
			}
			scale = 1 / dpr;
			metaEl.setAttribute('content', 'width=device-width,initial-scale=' + scale + ',maximum-scale=' + scale + ', minimum-scale=' + scale + ',user-scalable=no,shrink-to-fit=no');
			docEl.setAttribute('data-dpr', dpr);
			var recalc = function () {
				clientWidth = docEl.clientWidth;
				if (!clientWidth) return;
				docEl.style.fontSize = clientWidth / 10 + 'px';
				if (document.body) {
					document.body.style.fontSize = docEl.style.fontSize;
				}
				if (dpr == 1) {
					var fontEl = document.getElementById('init_style');
					var pxscale = clientWidth / 750;
					docEl.firstElementChild.appendChild(fontEl);
					fontEl.innerHTML = '.px-scale{transform:scale(' + pxscale + ') !important;-webkit-transform:scale(' + pxscale + ') !important;}'; //雪碧图缩放
				}
			};
			recalc();
			window.rem2px = function (v) {
				v = parseFloat(v);
				return v * rem;
			};
			window.px2rem = function (v) {
				v = parseFloat(v);
				return v / rem;
			};
			window.dpr = dpr;
			window.rem = rem;
			if (!doc.addEventListener) return;
			win.addEventListener(resizeEvt, recalc, false);
			doc.addEventListener('DOMContentLoaded', recalc, false);
		})(document, window);
	</script>
```