Update field outside variable set when row is deleted in MRVS

[Ruchi Kumari1]

I am working on a script where i need to update a list collector field when a row is deleted in MRVS.
My catalog is defined in following format:
1. List collector field (outside any variable set) > This allows to select multiple users
2. MRVS with 3 variables defined : reqFor, assetname, serialnumber;

When user is selected, MRVS adds row with details (reqFor, assetname, serialnumber) of selected user. If user is removed, MRVS is getting updated. //working

If I remove a row from MRVS, list collector should be updated. Basically, if i remove any row, user removed from MRVS should also be removed from list field. That is both list collector and MRVS should be in sync. //This is not working.
*I want this onchange to execute only when row is removed*

The resources available in community talks about script in widget but I need that in my client script. To start with, I am trying an onchange client script in MRVS with field value of reqFor. But, I am not getting the alert itself.
any suggestion on how i can achieve this. ?

var requestedFor = g_form.getValue('list_the_existing_machine_name');// MRVS internal name
var parser = JSON.parse(requestedFor);
alert(parser.length);//NO ALERT

/*var valueToRemove ='';
var userListCollector = parent.g_form.getValue('my_list_collector');
var listArr = userListCollector.split(',');
var index = listArr.indexOf(valueToRemove);
if(index! == -1){
listArr.splice(index,1);
parent.g_form.setValue(userListCollector, listArr.join(','));*/

Does onchange script work at all when row is removed ? I tried giving a simple alert on change of variable in MRVs and i did not get that alert as well.

[Ankur Bawiskar · Accepted solution]

@Ruchi Kumari1 

You cannot easily determine using client script etc on MRVS whether row was added/removed.

you can determine if row is added or removed using this workaround and then accordingly modify the outside list collector variable

MRVS detect when a row is removed or deleted 

If my response helped please mark it correct and close the thread so that it benefits future readers.