window.navigator

The navigator is an object that has some information about the browser. One property is navigator.userAgent, which is a long string of browser identification.

window.navigator.userAgent

//Firefox	"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.12) Gecko/20080201
//IE	Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30)
//Chrome	Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Because the browsers have different capabilities, developers can use userAgent string to identify the browser and provide different versions of the code.

Example to identify different browsers.

snippet

if (navigator.userAgent.indexOf("Chrome") > -1) {
    sBrowser = "Google Chrome";
} else if (navigator.userAgent.indexOf("Safari") > -1) {
    sBrowser = "Apple Safari";
} else if (navigator.userAgent.indexOf("Opera") > -1) {
    sBrowser = "Opera";
} else if (navigator.userAgent.indexOf("Firefox") > -1) {
    sBrowser = "Mozilla Firefox";
} else if (navigator.userAgent.indexOf("MSIE") > -1) {
    sBrowser = "Microsoft Internet Explorer";
}
console.log("You are using: " + sBrowser);

It is better not to rely on the user agent string as it's hard to keep track of all browsers and their different versions. It's much easier to simply check if the feature you intend to use is indeed available in the user's browser.

Example

snippet

if (typeof window.addEventListener === 'function') {
    // feature is supported, let's use it
} else {
    // this feature is not supported, go another way
}

Navigator Object Properties

Property	Description
appCodeName	Returns the code name of the browser
appName	Returns the name of the browser
appVersion	Returns the version information of the browser
cookieEnabled	Determines whether cookies are enabled in the browser
geolocation	Returns a Geolocation object that can be used to locate the user's position
language	Returns the language of the browser
onLine	Determines whether the browser is online
platform	Returns for which platform the browser is compiled
product	Returns the engine name of the browser
userAgent	Returns the user-agent header sent by the browser to the server

Navigator Object Methods

Method	Description
javaEnabled()	Specifies whether or not the browser has Java enabled
taintEnabled()	Removed in JavaScript version 1.2. Specifies whether the browser has data tainting enabled