How can you detect the version of a browser?

Question

I\'ve been searching around for code that would let me detect if the user visiting the website has Firefox 3 or 4. All I have found is code to detect the type of browser but

Answer 1

I wrote a version detector based on Hermann Ingjaldsson's answer, but more robust and which returns an object with name/version data in it. It covers the major browsers but I don't bother with the plethora of mobile ones and minor ones:

function getBrowserData(nav) {
    var data = {};

    var ua = data.uaString = nav.userAgent;
    var browserMatch = ua.match(/(opera|chrome|safari|firefox|msie|trident(?=\/))\/?\s*([\d\.]+)/i) || [];
    if (browserMatch[1]) { browserMatch[1] = browserMatch[1].toLowerCase(); }
    var operaMatch = browserMatch[1] === 'chrome';
    if (operaMatch) { operaMatch = ua.match(/\bOPR\/([\d\.]+)/); }

    if (/trident/i.test(browserMatch[1])) {
        var msieMatch = /\brv[ :]+([\d\.]+)/g.exec(ua) || [];
        data.name = 'msie';
        data.version = msieMatch[1];
    }
    else if (operaMatch) {
        data.name = 'opera';
        data.version = operaMatch[1];
    }
    else if (browserMatch[1] === 'safari') {
        var safariVersionMatch = ua.match(/version\/([\d\.]+)/i);
        data.name = 'safari';
        data.version = safariVersionMatch[1];
    }
    else {
        data.name = browserMatch[1];
        data.version = browserMatch[2];
    }

    var versionParts = [];
    if (data.version) {
        var versionPartsMatch = data.version.match(/(\d+)/g) || [];
        for (var i=0; i < versionPartsMatch.length; i++) {
            versionParts.push(versionPartsMatch[i]);
        }
        if (versionParts.length > 0) { data.majorVersion = versionParts[0]; }
    }
    data.name = data.name || '(unknown browser name)';
    data.version = {
        full: data.version || '(unknown full browser version)',
        parts: versionParts,
        major: versionParts.length > 0 ? versionParts[0] : '(unknown major browser version)'
    };

    return data;
};

It can then be used like this:

var brData = getBrowserData(window.navigator || navigator);
console.log('name: ' + brData.name);
console.log('major version: ' + brData.version.major);
// etc.