Get browser and computer zoom level with JavaScript

If we can get the default zoom of the computer through JavaScript, it will be very helpful for page adaptation. Below is the JavaScript code:

function detectZoom() {
      let ratio = 0
      const screen = window.screen
      const 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

    },



    After calculation, use zoom to shrink the page