How to stop duplicates entering in MRVS based on MRVS Variables(Applies Catalog item/ServicePortal)

[JackieZhang]

I have req to stop the duplicates entering in MRVS.

MRVS Internal name is temp_workers_for_create_accounts

I write onsubmit client script under the variable set. but not working and  g_form.getValue('temp_workers_for_create_accounts') is always empty. 

function onSubmit() {

    debugger;

    var mrvsJson = g_form.getValue('temp_workers_for_create_accounts');

    var name =  g_form.getValue('name');

    var mrvsRows = [];

    if (mrvsJson && mrvsJson.trim() !== '' && mrvsJson !== '[]') {

        mrvsRows = JSON.parse(mrvsJson);

    }

    if (mrvsRows.length === 0) return true;

    for (var i = 0; i < mrvsRows.length; i++) {

        var currentSysId = (mrvsRows[i]['name'] || '').trim();

        if (currentSysId== name) {

            g_form.addErrorMessage('Duplicate Temp Worker detected. This Temp Worker has already been added in the MRVS.');

            return false;

        }

    }

    return true;

}