Conditional action on a form

In this example, the script checks form AP10 for a particular vendor class (SUP) and if true, requires the user to add an email address.

function FORM_OnBeforeTransaction(fc)
{
    const sClassCheck = "SUP";
    if (fc === "A" || fc === "C")
    {
        if (lawForm.getFormValue("text4") === sClassCheck
            && lawForm.getFormValue("text34") === "")
        {
            let s = "An email address (at the bottom of the Contact page) ";
            s += "is required to be entered for a vendor with a ";
            s += "vendor class of " + sClassCheck + ".";
            portalWnd.cmnDlg.messageBox(s);
            return false;
        }
    }
    return true;
}