js获取浏览器当前缩放比例

废话不多说直接上代码

  function detectZoom() {
            var ratio = 0,//浏览器当前缩放比
                screen = window.screen,//获取屏幕
                ua = navigator.userAgent.toLowerCase();//判断登陆端是pc还是手机

            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);
            }
            if (ratio!=100) {
                layer.msg("您当前的窗口缩放比例为" + ratio + "%建议您的窗口比例调为100%，窗口比例不为100%可能导致页面排版错乱");//这里layer是layui框架自带弹窗，如果不是layui可以使用alert（）代替；
            }
        }