What is the Best way to do Browser Detection in Javascript?

Question

In one of my Web Development classes we where asked to create a script that detects NE4,NE6+,IE4,IE6+ Browsers that display a compatable CSS script for each browser.

he gave us an article to read about these and the article mentioned this site

one of the students said this

The best choice for javascript compatibility is to test for browser capabilities when you want to do something. One of the main reasons for this is that in the future, more and more browsers will be created.

Now my questions is this which way is the best way to detect the users browser object detection or using the Navigator Object?

Answer 1

The standard way to detect what browser is used is to check the user agent supplied.

var BrowserDetect = {
    init: function () {
        this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
        this.version = this.searchVersion(navigator.userAgent)
            || this.searchVersion(navigator.appVersion)
            || "an unknown version";
        this.OS = this.searchString(this.dataOS) || "an unknown OS";
    },
    searchString: function (data) {
        for (var i=0;i<data.length;i++) {
            var dataString = data[i].string;
            var dataProp = data[i].prop;
            this.versionSearchString = data[i].versionSearch || data[i].identity;
            if (dataString) {
                if (dataString.indexOf(data[i].subString) != -1)
                    return data[i].identity;
            }
            else if (dataProp)
                return data[i].identity;
        }
    },
    searchVersion: function (dataString) {
        var index = dataString.indexOf(this.versionSearchString);
        if (index == -1) return;
        return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
    },
    dataBrowser: [
        {
            string: navigator.userAgent,
            subString: "Chrome",
            identity: "Chrome"
        },
        {   string: navigator.userAgent,
            subString: "OmniWeb",
            versionSearch: "OmniWeb/",
            identity: "OmniWeb"
        },
        {
            string: navigator.vendor,
            subString: "Apple",
            identity: "Safari",
            versionSearch: "Version"
        },
        {
            prop: window.opera,
            identity: "Opera"
        },
        {
            string: navigator.vendor,
            subString: "iCab",
            identity: "iCab"
        },
        {
            string: navigator.vendor,
            subString: "KDE",
            identity: "Konqueror"
        },
        {
            string: navigator.userAgent,
            subString: "Firefox",
            identity: "Firefox"
        },
        {
            string: navigator.vendor,
            subString: "Camino",
            identity: "Camino"
        },
        {       // for newer Netscapes (6+)
            string: navigator.userAgent,
            subString: "Netscape",
            identity: "Netscape"
        },
        {
            string: navigator.userAgent,
            subString: "MSIE",
            identity: "Explorer",
            versionSearch: "MSIE"
        },
        {
            string: navigator.userAgent,
            subString: "Gecko",
            identity: "Mozilla",
            versionSearch: "rv"
        },
        {       // for older Netscapes (4-)
            string: navigator.userAgent,
            subString: "Mozilla",
            identity: "Netscape",
            versionSearch: "Mozilla"
        }
    ],
    dataOS : [
        {
            string: navigator.platform,
            subString: "Win",
            identity: "Windows"
        },
        {
            string: navigator.platform,
            subString: "Mac",
            identity: "Mac"
        },
        {
               string: navigator.userAgent,
               subString: "iPhone",
               identity: "iPhone/iPod"
        },
        {
            string: navigator.platform,
            subString: "Linux",
            identity: "Linux"
        }
    ]

};
BrowserDetect.init();

http://www.quirksmode.org/js/detect.html