replied on March 31, 2017
Hello,
Forms actually does support URL parameters, so for instance if you have a variable named UserId in the form http://hostName/Forms/Form/myForm, you can automatically supply that using http://hostName/Forms/Form/myForm?UserId=1234 for example.
If your solution uses cookies you can access those as a semicolon-delimited string with the JavaScript document.cookie, but I would personally recommend against this as it would depend on the end user having cookies enabled in the browser, which may or may not be appropriate to take as a given.
Regards
Clarification: This is if you need the user ID to fill a field in a form; if you are actually trying to log into Forms at the same time, there's no out-of-the-box method for automatic login, as it would depend on what type of authentication Forms is configured to use (LFS vs LFDS). If a user is not currently logged into Forms and attempts to navigate to such a URL, they will be prompted to log into Forms and then will be redirected to the form with the pre-populated User ID field.