頁面縮放監測

function detectZoom () {
  var ratio = 0,
    screen = window.screen,
    ua = navigator.userAgent.toLowerCase();

  if (window.devicePixelRatio !== undefined) {

    ratio = window.devicePixelRatio;
  } else if (~ua.indexOf('msie')) {

    if (screen.deviceXDPI && screen.logicalXDPI) {
      ratio = screen.deviceXDPI / screen.logicalXDPI;
    }
  } else if (window.outerWidth !== undefined && window.innerWidth !== undefined) {

    ratio = window.outerWidth / window.innerWidth;
  }

  if (ratio) {
    ratio = Math.round(ratio * 100);
  }

  return ratio;
};
let result = detectZoom()

轉載：https://www.jb51.net/article/55753.htm