User-agent string changes
Each release of Internet Explorer updates the user-agent string; here's what's changed recently.
For many legacy websites, some of the most visible updates for Internet Explorer 11 involve the user-agent string. Here's what's reported for IE11 on Windows 8.1:
As with previous versions of Internet Explorer, portions of user-agent string vary according to the environment. Here's the string for IE11 on Windows 7:
If you compare these values to those reported by earlier reported by earlier versions of Internet Explorer, you'll find the following changes:
- The compatible ("compatible") and browser ("MSIE") tokens have been removed.
- The "like Gecko" token has been added (for consistency with other browsers).
- The version of the browser is now reported by a new revision ("rv") token.
These changes help prevent IE11 from being (incorrectly) identified as an earlier version.
As with earlier versions, compatibility view affects the user-agent string. When IE11 displays a page in compatibility view, the user agent string reflects the older format shown in this example:
Due to the variety of conditions that affect the user-agent string (and the fact that elements of the string change for each release of the browser, the operating system, and other environmental factors), websites that rely on specific user-agent values should be updated to use alternate techniques.
The assumptions underlying such tests tend to lead to false positive results when browsers are updated. Instead, detect features as you need them and use progressive enhancement to provide simplified experiences for browsers or devices that do not support the features you need.
In rare cases, it may be necessary to uniquely identify IE11. Use the Trident token to do so.
For Internet Explorer 10, the following changes were made to the user agent string:
- The value of the Version token ("MSIE") was changed to "10.0".
- The value of the Trident token ("Trident") became "6.0".
- For Windows 8, the value of the Platform token ("Windows NT") was changed to "6.2".
Internet Explorer 9, reflected the following changes to the user agent string:
- The application token became "Mozilla/5.0".
- The version token was updated to "MSIE 9.0".
- The Trident token updated to "Trident/5.0".
- The user-agent string was modified to exclude tokens describing tools, add-ons, and other optional software.
Earlier versions of the browser included Pre-Platform and Post-platform registry value tokens in the user-agent string. However, this led to performance issues for customers of certain tools and add-ons. As a result, these tokens are now reported only through the navigator.userAgent property.
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