javascript 判断浏览器IE版本

主要js与解释

<script> 
    function IEVersion() {
        var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串  
        var isIE = userAgent.indexOf("compatible") > -1 && userAgent.indexOf("MSIE") > -
                                1; //判断是否IE<11浏览器  
        var isEdge = userAgent.indexOf("Edge") > -1 && !isIE; //判断是否IE的Edge浏览器  
        var isIE11 = userAgent.indexOf('Trident') > -1 && userAgent.indexOf("rv:11.0") > -1;
        if (isIE) {
            var reIE = new RegExp("MSIE (\\d+\\.\\d+);");
            reIE.test(userAgent);
            var fIEVersion = parseFloat(RegExp["$1"]);
            if (fIEVersion == 7) {
                alert("ie版本过低")
                window.location.href =
                                        "https://support.microsoft.com/zh-cn/help/17621/internet-explorer-downloads"
            } else if (fIEVersion == 8) {
                alert("ie版本过低")
                window.location.href =
                                        "https://support.microsoft.com/zh-cn/help/17621/internet-explorer-downloads"
            } else if (fIEVersion == 9) {
                alert("ie版本过低")
                window.location.href =
                                        "https://support.microsoft.com/zh-cn/help/17621/internet-explorer-downloads"
            } else if (fIEVersion == 10) {
                return 10;
            } else {
                return 6; //IE版本<=7
            }
        } else if (isEdge) {
            return 'edge'; //edge
        } else if (isIE11) {
            return 11; //IE11  
        } else {
            return -1; //不是ie浏览器
        }
    }
</script>