关于前端iOS9兼容问题

这个其他系统都没问题，就是iOS9不行

<script>
const maxWidth = 750
function setRem(){
  let htmlEle = document.querySelector('html')
  let docWidth = document.documentElement.clientWidth
  let realWidth = docWidth > maxWidth ? maxWidth : docWidth
  htmlEle.style.fontSize = realWidth / 7.5 + 'px'
}
setRem()
window.addEventListener('resize', setRem, false)
</script>

后来Google找到了个，换上去看，啊，真的解决了

<script>
;(function (doc, win) {
   var docEl = doc.documentElement,
      resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
      recalc = function() {
         var clientWidth = docEl.clientWidth;
         if (!clientWidth) {
            return;
         }
         if ( clientWidth > 500) {
            clientWidth = 500;
         }
         docEl.style.fontSize = 100 * (clientWidth / 750) + 'px';
      };
   if (!doc.addEventListener) {
      return;
   } else {
      win.addEventListener(resizeEvt, recalc, false);
      doc.addEventListener('DOMContentLoaded', recalc, false);
   }
})(document, window);
</script>

代码来源：http://www.cnblogs.com/bagnliu/p/8288501.html