试试这个

alert(Math.round(window.devicePixelRatio * 100));

现在的情况比刚提出这个问题时还要糟糕。通过阅读我所能找到的所有回复和博客文章，这里有一个总结。我还设置了这个页面来测试所有这些测量缩放级别的方法。[↑断裂链接。存档副本→此处]。

编辑(2011-12-12):我添加了一个可以克隆的项目:https://github.com/tombigel/detect-zoom

IE8: screen.deviceXDPI / screen.logicalXDPI (or, for the zoom level relative to default zoom, screen.systemXDPI / screen.logicalXDPI) IE7: var body = document.body,r = body.getBoundingClientRect(); return (r.left-r.right)/body.offsetWidth; (thanks to this example or this answer) FF3.5 ONLY: screen.width / media query screen width (see below) (takes advantage of the fact that screen.width uses device pixels but MQ width uses CSS pixels--thanks to Quirksmode widths) FF3.6: no known method FF4+: media queries binary search (see below) WebKit: https://www.chromestatus.com/feature/5737866978131968 (thanks to Teo in the comments) WebKit: measure the preferred size of a div with -webkit-text-size-adjust:none. WebKit: (broken since r72591) document.width / jQuery(document).width() (thanks to Dirk van Oosterbosch above). To get ratio in terms of device pixels (instead of relative to default zoom), multiply by window.devicePixelRatio. Old WebKit? (unverified): parseInt(getComputedStyle(document.documentElement,null).width) / document.documentElement.clientWidth (from this answer) Opera: document.documentElement.offsetWidth / width of a position:fixed; width:100% div. from here (Quirksmode's widths table says it's a bug; innerWidth should be CSS px). We use the position:fixed element to get the width of the viewport including the space where the scrollbars are; document.documentElement.clientWidth excludes this width. This is broken since sometime in 2011; I know no way to get the zoom level in Opera anymore. Other: Flash solution from Sebastian Unreliable: listen to mouse events and measure change in screenX / change in clientX

这里是Firefox 4的二进制搜索，因为我不知道它暴露在哪里:

<style id=binarysearch></style>
<div id=dummyElement>Dummy element to test media queries.</div>
<script>
var mediaQueryMatches = function(property, r) {
  var style = document.getElementById('binarysearch');
  var dummyElement = document.getElementById('dummyElement');
  style.sheet.insertRule('@media (' + property + ':' + r +
                         ') {#dummyElement ' +
                         '{text-decoration: underline} }', 0);
  var matched = getComputedStyle(dummyElement, null).textDecoration
      == 'underline';
  style.sheet.deleteRule(0);
  return matched;
};
var mediaQueryBinarySearch = function(
    property, unit, a, b, maxIter, epsilon) {
  var mid = (a + b)/2;
  if (maxIter == 0 || b - a < epsilon) return mid;
  if (mediaQueryMatches(property, mid + unit)) {
    return mediaQueryBinarySearch(
        property, unit, mid, b, maxIter-1, epsilon);
  } else {
    return mediaQueryBinarySearch(
        property, unit, a, mid, maxIter-1, epsilon);
  }
};
var mozDevicePixelRatio = mediaQueryBinarySearch(
    'min--moz-device-pixel-ratio', '', a, b, maxIter, epsilon);
var ff35DevicePixelRatio = screen.width / mediaQueryBinarySearch(
    'min-device-width', 'px', 0, 6000, 25, .0001);
</script>

我有这个解决方案只适用于手机(在Android上测试):

jQuery(function($){

zoom_level = function(){

    $("body").prepend('<div class="overlay" ' +
                'style="position:fixed; top:0%; left:0%; ' +
                'width:100%; height:100%; z-index:1;"></div>');

    var ratio = $("body .overlay:eq(0)").outerWidth() / $(window).width();
    $("body .overlay:eq(0)").remove();

    return ratio;
}

alert(zoom_level());

});

如果你想要缩放级别在缩放移动之后，你可能不得不设置一个小的超时，因为呈现延迟(但我不确定，因为我没有测试它)。

在Chrome

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

这是一个很久以前发布的问题，但今天当我在寻找相同的答案“如何检测放大和缩小事件”时，我找不到一个适合所有浏览器的答案。

就像现在一样:对于Firefox/Chrome/IE8和IE9，放大和缩小会触发一个窗口。调整大小事件。 可以使用以下方法捕获:

$(window).resize(function() {
//YOUR CODE.
});

这是针对Chrome的，在user800583回答之后…

我花了几个小时研究这个问题，并没有找到更好的方法，但是:

有16个“zoomLevel”而不是10个 当Chrome是全屏/最大化的比率是window. outerwidth /window。innerWidth，如果不是，比率似乎是(window. outerwidth -16)/window。innerWidth，但是第一种情况可以被第二种情况接近。

所以我想到了下面这些……

但是这种方法有局限性:例如，如果您在应用程序窗口中使用手风琴(快速放大和减小窗口的宽度)，那么尽管缩放没有改变(可能outerWidth和innerWidth没有同时更新)，但您将在缩放级别之间获得间隙。

var snap = function (r, snaps)
{
    var i;
    for (i=0; i < 16; i++) { if ( r < snaps[i] ) return i; }
};
var w, l, r;
w = window.outerWidth, l = window.innerWidth;
return snap((w - 16) / l,
            [ 0.29, 0.42, 0.58, 0.71, 0.83, 0.95, 1.05, 1.18, 1.38, 1.63, 1.88, 2.25, 2.75, 3.5, 4.5, 100 ],
);

如果你想要因子:

var snap = function (r, snaps, ratios)
{
    var i;
    for (i=0; i < 16; i++) { if ( r < snaps[i] ) return eval(ratios[i]); }
};
var w, l, r;
w = window.outerWidth, l = window.innerWidth;
return snap((w - 16) / l,
            [ 0.29, 0.42, 0.58, 0.71, 0.83, 0.95, 1.05, 1.18, 1.38, 1.63, 1.88, 2.25, 2.75, 3.5, 4.5, 100 ],
            [ 0.25, '1/3', 0.5, '2/3', 0.75, 0.9, 1, 1.1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5 ]
);