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    window.navigator.userAgent Redirect 1

    Returns the user agent string for the current browser.


    var ua = window.navigator.userAgent;


    ua stores the user agent string value of the current browser.

    The window.navigator.userAgent property is read-write; it has no default value.

    The user agent string is built on a formal structure which can be decomposed into several pieces of info. Each of these pieces of info comes from other navigator properties which are also settable by the user. Gecko-based browsers comply with the following general structure:

    userAgent = appCodeName/appVersion number (Platform; Security; OS-or-CPU; 
    Localization; rv: revision-version-number) product/productSub 
    Application-Name Application-Name-version


    // alerts "Mozilla/5.0 (Windows; U; Win98; en-US; rv:0.9.2) Gecko/20010725 Netscape6/6.1"


    Browser identification based on detecting the user agent string is unreliable and is not recommended, as the user agent string is user configurable. For example:

    • In Firefox, you can change the preference general.useragent.override in about:config. Some Firefox extensions do that; however, this only changes the HTTP header that gets sent, and doesn't affect browser detection performed by JavaScript code.
    • Opera 6+ allows users to set the browser identification string via a menu
    • Microsoft Internet Explorer uses the Windows registry
    • Safari and iCab allow users to change the browser user agent string to predefined Internet Explorer or Netscape strings via a menu.


    Specification Status Comment
    WHATWG HTML Living Standard
    The definition of 'NavigatorID.userAgent' in that specification.
    Living Standard Initial definition

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)


    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy
    Last updated by: Sheppy,
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