title: res.redirect('back') with parameters
body: <p>I have a register form on every page of my website.  During registration some error may occur.  After catching the error, I have to return the user to the previous page, showing some error message.  The problem is that I do not know from which page the user performed the registration, so I use <code>res.redirect('back');</code>.  However, I cannot just redirect user back, I have to display the error message also, so I have to pass some argument.   But <code>res.redirect('back', (reg_error:'username')})</code> cannot be used directly because <code>res.redirect()</code> does not support parameters.  How can I render the previous page with some parameter?</p>