About 3 common packages of rem adaptation

export function rem (doc, win) {
  let docEl = doc.documentElement;
  //Considering and being compatible with screen rotation events let resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
  let recalc = function () {
            var clientWidth = docEl.clientWidth;
            if (!clientWidth) return;
            if (clientWidth >= 750) {
                 docEl.style.fontSize = '100px';
            } else {
                 docEl.style.fontSize = 100 * (clientWidth / 750) + 'px';
            }
      };

   if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false); // Adapt to screen size and rotation doc.addEventListener('DOMContentLoaded', recalc, false); // Adapt to the page when it is first opened recalc();
};

export function rem() {
  var fz = document.querySelector('html').offsetWidth / 7.5; //Design drawing 750 1rem=100px
  document.querySelector('html').style.fontSize =
    fz <= 100 ? fz + 'px' : '100px';
  window.onresize = function() {
    rem();
  };
};

export function rem() {
  document.documentElement.style.fontSize = window.innerWidth / 7.5 + 'px'; //1rem = 100px
  document.body.style.fontSize = '14px'; // Restore the font size on the body to avoid oversized fonts without style on the page}