在Chrome

var ratio = (screen.availWidth / document.documentElement.clientWidth);
var zoomLevel = Number(ratio.toFixed(1).replace(".", "") + "0");

I found this article enormously helpful. Huge thanks to yonran. I wanted to pass on some additional learning I found while implementing some of the techniques he provided. In FF6 and Chrome 9, support for media queries from JS was added, which can greatly simplify the media query approach necessary for determining zoom in FF. See the docs at MDN here. For my purposes, I only needed to detect whether the browser was zoomed in or out, I had no need for the actual zoom factor. I was able to get my answer with one line of JavaScript:

var isZoomed = window.matchMedia('(max--moz-device-pixel-ratio:0.99), (min--moz-device-pixel-ratio:1.01)').matches;

结合IE8+和Webkit解决方案(它们也是单行的)，我能够在只有几行代码的情况下检测到绝大多数浏览器的缩放效果。

这个答案是基于user1080381的答案上devicePixelRatio返回错误的注释。

我发现在使用台式机、Surface Pro 3和Surface Pro 4时，这个命令在某些情况下也会错误地返回。

我发现它在我的桌面上是有效的，但是SP3和SP4给出的数字是不同的。

不过我注意到，SP3的缩放级别是我预期的1.5倍。当我查看显示设置时，SP3实际上被设置为150%，而不是我桌面上的100%。

因此，注释的解决方案应该是将返回的缩放级别除以当前所在机器的缩放比例。

我可以通过以下方法在Windows设置中获得比例:

ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_DesktopMonitor");
double deviceScale = Convert.ToDouble(searcher.Get().OfType<ManagementObject>().FirstOrDefault()["PixelsPerXLogicalInch"]);
int standardPixelPerInch = 96;
return deviceScale / standardPixelPerInch;

所以在我的SP3的情况下，这是这段代码在100%缩放时的样子:

devicePixelRatio = 1.5
deviceScale = 144
deviceScale / standardPixelPerInch = 1.5
devicePixelRatio / (deviceScale / standardPixelPerInch) = 1

乘以user1080381的原始答案中的100，然后将得到100(%)的缩放。

没有在IE中测试这个，但是如果你创建一个元素elem with

min-width: 100%

然后

window.document.width / elem.clientWidth

将为您提供浏览器缩放级别(包括document.body.style.zoom因子)。

截至2016年1月，我有一个解决方案。在Chrome, Firefox和MS Edge浏览器中测试工作。

The principle is as follows. Collect 2 MouseEvent points that are far apart. Each mouse event comes with screen and document coordinates. Measure the distance between the 2 points in both coordinate systems. Although there are variable fixed offsets between the coordinate systems due to the browser furniture, the distance between the points should be identical if the page is not zoomed. The reason for specifying "far apart" (I put this as 12 pixels) is so that small zoom changes (e.g. 90% or 110%) are detectable.

参考: https://developer.mozilla.org/en/docs/Web/Events/mousemove

步骤:

添加一个鼠标移动监听器 窗口。addEventListener("鼠标移动"，函数(事件){ //处理事件 })； 从鼠标事件中捕获4个测量值: 事件。clientX、事件。clientY、事件。screenX, event.screenY 测量客户端系统中两点之间的距离d_c 测量屏幕系统中两点之间的距离d_s 如果d_c != d_s，则应用缩放。两者之间的差别告诉你缩放的大小。

注意:很少做距离计算，例如，当你可以采样一个新的鼠标事件，它离前一个事件很远的时候。

限制:假设用户将移动鼠标至少一点，缩放是不可知的，直到这个时候。

一个变通的FireFox 16+找到DPPX(缩放级别)纯粹与JavaScript:

var dppx = (function (precision) {
  var searchDPPX = function(level, min, divisor) {
    var wmq = window.matchMedia;
    while (level >= min && !wmq("(min-resolution: " + (level/divisor) + "dppx)").matches) {
      level--;
    }
    return level;
  };

  var maxDPPX = 5.0; // Firefox 22 has 3.0 as maximum, but testing a bit greater values does not cost much
  var minDPPX = 0.1; // Firefox 22 has 0.3 as minimum, but testing a bit smaller values does not cost anything
  var divisor = 1;
  var result;
  for (var i = 0; i < precision; i++) {
    result = 10 * searchDPPX (maxDPPX, minDPPX, divisor);
    maxDPPX = result + 9;
    minDPPX = result;
    divisor *= 10;
  }

  return result / divisor;
}) (5);