移动端给不同设备设置不同的字体大小

(function flexible(window, document) {
  var docEl = document.documentElement;
  var dpr = window.devicePixelRatio || 1;
  var isHS = false;

  // adjust body font size
  function setBodyFontSize() {
    if (document.body) {
      // document.body.style.fontSize = (12 * dpr) + 'px'
    } else {
      document.addEventListener('DOMContentLoaded', setBodyFontSize);
    }
  }
  setBodyFontSize();

  //判断手机横竖屏状态
  function judgeHorizontalScreen() {
    // if (window.orientation === 180 || window.orientation === 0) {
    //   isHS = false
    // }
    // if (window.orientation === 90 || window.orientation === -90) {
    //   isHS = true
    // }
    setRemUnit();
  }
  judgeHorizontalScreen();
  window.addEventListener('onorientationchange' in window ? 'orientationchange' : 'resize', judgeHorizontalScreen, false);

  // set 1rem = viewWidth / 10
  function setRemUnit() {
    var rem = docEl.clientHeight < docEl.clientWidth ? docEl.clientHeight / 10 : docEl.clientWidth / 10;
    docEl.style.fontSize = rem + 'px';
  }

  setRemUnit();

  // reset rem unit on page resize
  window.addEventListener('resize', setRemUnit);
  window.addEventListener('pageshow', function (e) {
    if (e.persisted) {
      setRemUnit();
    }
  });

  // detect 0.5px supports
  if (dpr >= 2) {
    var fakeBody = document.createElement('body');
    var testElement = document.createElement('div');
    testElement.style.border = '.5px solid transparent';
    fakeBody.appendChild(testElement);
    docEl.appendChild(fakeBody);
    if (testElement.offsetHeight === 1) {
      docEl.classList.add('hairlines');
    }
    docEl.removeChild(fakeBody);
  }
})(window, document);