What is User Agent string (CSE HTML Validator standard)

For technical support for all editions of CSS HTML Validator. Includes bug reports.
Post Reply
bobtobey
Rank 0 - Newcomer
Rank 0 - Newcomer
Posts: 1
Joined: Tue Feb 24, 2015 6:53 pm

What is User Agent string (CSE HTML Validator standard)

Post by bobtobey » Fri Mar 27, 2015 1:40 pm

Hello,

I have what is probably an easy question, but in the "Open URL from the web dialog" under the Agent drop down choices there is "CSE HTML Validator standard (https://www.htmlvalidator.com/)" listed among all the choices. It does not seem to give the same results as using "not specified". What is its use? Does it represent something else or is it not meant to be used?

Thank you for your help in advance.

Bob

User avatar
Albert Wiersch
Site Admin
Site Admin
Posts: 3453
Joined: Sat Dec 11, 2004 9:23 am
Location: Near Dallas, TX
Contact:

Re: What is User Agent string (CSE HTML Validator standard)

Post by Albert Wiersch » Fri Mar 27, 2015 4:06 pm

Hi Bob,

Some websites return different HTML based on the user agent. This option allows you to set a specific user agent string in order to simulate a request from various browsers (and versions of them). Whether or not you get back the same document from the server when using different user agent strings depends on whether the server (or scripting language that is generating the page) looks at the user agent string that was given in the request and whether it returns a different or altered document based on the user agent string.

As an example, some sites may be configured to recognize older or obsolete browsers based on the given user agent, and might therefore (if an old or obsolete browser is detected) return a basic version of the page or redirect the user to a page telling them to upgrade their browser.

Most servers probably don't send back different documents because it's generally not a good idea to do so but I'm sure there are exceptions.
Image
Albert Wiersch

Post Reply