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

Here this has better compatibility then @kennebec snippet;
will return browser name and version (returns 72 instead of 72.0.3626.96).

Tested on Safari, Chrome, Opera, Firefox, IE, Edge, UCBrowser, also on mobile.

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;
}