获取移动设备最大化大小

function getZoom() {
  var screenWidth =
    Math.abs(window.orientation) === 90
      ? Math.max(screen.height, screen.width)
      : Math.min(screen.height, screen.width);
  if (this.isAndroidMobileDevice() && !this.isNewChromeOnAndroid()) {
    screenWidth = screenWidth / window.devicePixelRatio;
  }
  var FixViewPortsExperiment =
    rendererModel.runningExperiments.FixViewport ||
    rendererModel.runningExperiments.fixviewport;
  var FixViewPortsExperimentRunning =
    FixViewPortsExperiment &&
    (FixViewPortsExperiment === "New" || FixViewPortsExperiment === "new");
  if (FixViewPortsExperimentRunning) {
    return screenWidth / window.innerWidth;
  } else {
    return screenWidth / document.body.offsetWidth;
  }
}