JavaScript code to Add/Subtract days from Date Object

let prevPremVal = null; // Initialize previous premium value


customrecord_jj_new_commi_report_ahap29SearchObj.run().each(function(result) {
    let isPremium = result.getValue(result.columns[36]); // Check if it's premium
    let tieredPremium = getTieredPremiumValue(result.getValue(result.columns[38]), result.getValue(result.columns[61]));


    log.debug("Is Premium:", isPremium);
    log.debug("Tiered Premium:", tieredPremium);


    // If isPremium is true and tieredPremium is valid, use tieredPremium
    // Otherwise, keep using prevPremVal
    let displayVal = (isPremium && tieredPremium !== null && tieredPremium !== undefined && tieredPremium !== '') 
                     ? tieredPremium 
                     : prevPremVal;


    log.debug("Display Value (Uses Previous if Empty or Condition Not Met):", displayVal);


    // Only update prevPremVal if isPremium is true and tieredPremium is valid
    if (isPremium && tieredPremium !== null && tieredPremium !== undefined && tieredPremium !== '') {
        prevPremVal = tieredPremium;
    }


    return true; // Continue iteration
});