一种简单的 rem 单位基准设置

function setRem(designWidth, maxWidth) {
      var htmlElm = document.documentElement;
      var pageWidth = htmlElm.getBoundingClientRect().width;
      pageWidth = Math.min(pageWidth ,maxWidth || designWidth);
      var rempx = 100*pageWidth/designWidth;
      htmlElm.style.fontSize = rempx+‘px‘;
      document.body.style.fontSize = ‘0.16rem‘; //16px
}


setRem(750,1920) //pc
setRem(750,680) //mobile