加上我自己对赫尔曼答案的实现。我需要操作系统检测，所以它被添加。还包括一些ES6代码(因为我们有一个转译器)，你可能需要es5化。

detectClient() {
    let nav = navigator.appVersion,
        os = 'unknown',
        client = (() => {
            let agent = navigator.userAgent,
                engine = agent.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [],
                build;

            if(/trident/i.test(engine[1])){
                build = /\brv[ :]+(\d+)/g.exec(agent) || [];
                return {browser:'IE', version:(build[1] || '')};
            }

            if(engine[1] === 'Chrome'){
                build = agent.match(/\bOPR\/(\d+)/);

                if(build !== null) {
                    return {browser: 'Opera', version: build[1]};
                }
            }

            engine = engine[2] ? [engine[1], engine[2]] : [navigator.appName, nav, '-?'];

            if((build = agent.match(/version\/(\d+)/i)) !== null) {
                engine.splice(1, 1, build[1]);
            }

            return {
              browser: engine[0],
              version: engine[1]
            };
        })();

    switch (true) {
        case nav.indexOf('Win') > -1:
            os = 'Windows';
        break;
        case nav.indexOf('Mac') > -1:
            os = 'MacOS';
        break;
        case nav.indexOf('X11') > -1:
            os = 'UNIX';
        break;
        case nav.indexOf('Linux') > -1:
            os = 'Linux';
        break;
    }        

    client.os = os;
    return client;
}

返回:对象{浏览器:"Chrome"，版本:"50"，操作系统:"UNIX"}

您可以看到浏览器显示的内容，并使用该信息记录或测试多个浏览器。

navigator.sayswho= (function(){ var ua= navigator.userAgent; var tem; var M= ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || []; if(/trident/i.test(M[1])){ tem= /\brv[ :]+(\d+)/g.exec(ua) || []; return 'IE '+(tem[1] || ''); } if(M[1]=== 'Chrome'){ tem= ua.match(/\b(OPR|Edge)\/(\d+)/); if(tem!= null) return tem.slice(1).join(' ').replace('OPR', 'Opera'); } M= M[2]? [M[1], M[2]]: [navigator.appName, navigator.appVersion, '-?']; if((tem= ua.match(/version\/(\d+)/i))!= null) M.splice(1, 1, tem[1]); return M.join(' '); })(); console.log(navigator.sayswho); // outputs: `Chrome 62`

在纯Javascript中，您可以在导航器上执行RegExp匹配。使用userAgent查找Firefox版本:

var uMatch = navigator.userAgent.match(/Firefox\/(.*)$/),
    ffVersion;
if (uMatch && uMatch.length > 1) {
    ffVersion = uMatch[1];
}

如果不是Firefox浏览器，ffVersion将未定义。

参见工作示例→

为什么不另一个解决方案:

navigator.userAgent.includes("Firefox")? log("Mozilla") :log("Chrome")

这里有更好的兼容性@kennebec snippet; 将返回浏览器名称和版本(返回72而不是72.0.3626.96)。

在Safari, Chrome, Opera, Firefox, IE, Edge, UCBrowser上测试，也在移动设备上测试。

function browser() {
    var userAgent = navigator.userAgent,
        match = userAgent.match(/(opera|chrome|crios|safari|ucbrowser|firefox|msie|trident(?=\/))\/?\s*(\d+)/i) || [],
        result = {},
        tem;

    if (/trident/i.test(match[1])) {
        tem = /\brv[ :]+(\d+)/g.exec(userAgent) || [];
        result.name = "Internet Explorer";
    } else if (match[1] === "Chrome") {
        tem = userAgent.match(/\b(OPR|Edge)\/(\d+)/);

        if (tem && tem[1]) {
            result.name = tem[0].indexOf("Edge") === 0 ? "Edge" : "Opera";
        }
    }
    if (!result.name) {
        tem = userAgent.match(/version\/(\d+)/i); // iOS support
        result.name = match[0].replace(/\/.*/, "");

        if (result.name.indexOf("MSIE") === 0) {
            result.name = "Internet Explorer";
        }
        if (userAgent.match("CriOS")) {
            result.name = "Chrome";
        }

    }
    if (tem && tem.length) {
        match[match.length - 1] = tem[tem.length - 1];
    }

    result.version = Number(match[match.length - 1]);

    return result;
}

var ua = navigator.userAgent;

if (/Firefox\//.test(ua))
   var Firefox = /Firefox\/([0-9\.A-z]+)/.exec(ua)[1];