<script type="text/javascript">

(function(doc, win) {

var docEl = doc.documentElement,

isIOS = navigator.userAgent.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/),

dpr = isIOS ? Math.min(win.devicePixelRatio, 3) : 1,

dpr = window.top === window.self ? dpr : 1, //被iframe引用时，禁止缩放

resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';

docEl.dataset.dpr = dpr;

var recalc = function() {

var width = docEl.clientWidth;

var designWidth=320;

if (width / dpr > designWidth) {

width = designWidth * dpr;

}

docEl.dataset.width = width

docEl.dataset.percent = 100 * (width / designWidth);

docEl.style.fontSize = 100 * (width / designWidth) + 'px';

};

recalc()

if (!doc.addEventListener) return;

win.addEventListener(resizeEvt, recalc, false);

})(document, window);

</script>