Post Message to embedded form in Salesforce

Let's say you need to pass in sensitive information, and you are not allowed to pass the variable in a query string.
What do you do? Simple - you use a post message.

Read how it's done:
In FormTitan

In Salesforce

Our Ctl extension: 
public class someContactServiceCtlClass { private Contact cont; public string hy {get; set;} public string hm {get; set;} public string hd {get; set;} public string hevents {get; set;} public someContactServiceCtlClass(ApexPages.StandardController stdController) { try{ this.cont = (Contact)stdController.getRecord(); cont = [select id, birthdate from contact where id=:cont.Id]; getHebDate(cont.Birthdate.year(), cont.Birthdate.month(), cont.Birthdate.day()); }catch(Exception ex){ system.debug(ex.getMessage()); system.debug('>>> ' + ex.getStackTraceString()); } } public void getHebDate(integer gy, integer gm,integer gd){ HttpRequest req = new HttpRequest(); string endpointUrl = 'https://www.hebcal.com/converter/?cfg=json&gy='+gy+'&gm='+gm+'&gd='+gd; req.setEndpoint(endpointUrl); req.setMethod('GET'); Http http = new Http(); HTTPResponse res = http.send(req); string resbody = res.getBody(); HebCal cal = (HebCal) JSON.deserialize(resbody,HebCal.class); string events = ''; if(cal.events !=null){ for(string ev : cal.events) { events+=ev +' ' ; } hevents = events; } hy = string.valueOf(cal.hy); hm = cal.hm; hd = string.valueOf(cal.hd); } class HebCal { public integer gy {get; set;} public integer gm {get; set;} public integer gd {get; set;} public integer hy {get; set;} public String hm {get; set;} public integer hd {get; set;} public String hebrew {get; set;} List<string> events = new List<string>(); } } Our VisualForce Page <apex:page standardController="Contact" extensions="someContactServiceCtlClass" lightningStylesheets="true"> <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script> $( document ).ready(function() { setTimeout(function(){ postMsg()}, 4000); }); function postMsg(){ var iframe = $("#ftEmbedForm") var contentWin = iframe[0].contentWindow; var data = JSON.stringify({events:"{!hevents}", hedate:"{!hd} {!hm} {!hy}"}); contentWin.postMessage(data, '*'); } </script> <h1>Congratulations</h1> This is your new Page <div> <apex:pageBlock title="Hebrew Birthdate"> <apex:outputText >{!hd} {!hm} {!hy} </apex:outputText> <p> <apex:outputText >{!hevents}</apex:outputText> </p> </apex:pageBlock> </div> <iframe Id='ftEmbedForm' onload="window.parent.scrollTo(0,0)" allowtransparency="true" src="https://yoursubdomain.docstitan.com/iframepostmessage?fld28={!Contact.Id}" frameborder="0" width="1000" height="794" scrolling="no"></iframe> </apex:page>
and the end result will look like this:


Watch the video!