How to use the node-opcua-service-subscription.checkDeadBand function in node-opcua-service-subscription

//      DataChange if (absolute value of (last cached value - current value) >
            //                                          (deadbandValue/100.0) * ((high-low) of EURange)))
            //
            // Specifying a deadbandValue outside of this range will be rejected and reported with the
            // StatusCode Bad_DeadbandFilterInvalid (see Table 27).
            // If the Value of the MonitoredItem is an array, then the deadband calculation logic shall be applied to
            // each element of the array. If an element that requires a DataChange is found, then no further
            // deadband checking is necessary and the entire array shall be returned.
            assert(self.node !== null, "expecting a valid address_space object here to get access the the EURange");

            if (self.node.euRange) {
                // double,double
                const rangeVariant = self.node.euRange.readValue().value;
                const range = rangeVariant.value.high - rangeVariant.value.high;
                assert(_.isFinite(range));
                return checkDeadBand(oldDataValue.value, newDataValue.value, DeadbandType.Percent, deadbandValue, range);

            }
            return true;
    }
}

function valueHasChanged(self, newDataValue, oldDataValue, deadbandType, deadbandValue) {

    assert(newDataValue instanceof DataValue);
    assert(oldDataValue instanceof DataValue);
    switch (deadbandType) {
        case DeadbandType.None:
            assert(newDataValue.value instanceof Variant);
            assert(newDataValue.value instanceof Variant);
            // No Deadband calculation should be applied.
            return checkDeadBand(oldDataValue.value, newDataValue.value, DeadbandType.None);
        case DeadbandType.Absolute:
            // AbsoluteDeadband
            return checkDeadBand(oldDataValue.value, newDataValue.value, DeadbandType.Absolute, deadbandValue);
        default:
            // Percent_2    PercentDeadband (This type is specified in Part 8).
            assert(deadbandType === DeadbandType.Percent);

            // The range of the deadbandValue is from 0.0 to 100.0 Percent.
            assert(deadbandValue >= 0 && deadbandValue <= 100);

            // DeadbandType = PercentDeadband
            // For this type of deadband the deadbandValue is defined as the percentage of the EURange. That is,
            // it applies only to AnalogItems with an EURange Property that defines the typical value range for the
            // item. This range shall be multiplied with the deadbandValue and then compared to the actual value change
            // to determine the need for a data change notification. The following pseudo code shows how the deadband
            // is calculated:

function valueHasChanged(self, newDataValue, oldDataValue, deadbandType, deadbandValue) {

    assert(newDataValue instanceof DataValue);
    assert(oldDataValue instanceof DataValue);
    switch (deadbandType) {
        case DeadbandType.None:
            assert(newDataValue.value instanceof Variant);
            assert(newDataValue.value instanceof Variant);
            // No Deadband calculation should be applied.
            return checkDeadBand(oldDataValue.value, newDataValue.value, DeadbandType.None);
        case DeadbandType.Absolute:
            // AbsoluteDeadband
            return checkDeadBand(oldDataValue.value, newDataValue.value, DeadbandType.Absolute, deadbandValue);
        default:
            // Percent_2    PercentDeadband (This type is specified in Part 8).
            assert(deadbandType === DeadbandType.Percent);

            // The range of the deadbandValue is from 0.0 to 100.0 Percent.
            assert(deadbandValue >= 0 && deadbandValue <= 100);

            // DeadbandType = PercentDeadband
            // For this type of deadband the deadbandValue is defined as the percentage of the EURange. That is,
            // it applies only to AnalogItems with an EURange Property that defines the typical value range for the
            // item. This range shall be multiplied with the deadbandValue and then compared to the actual value change
            // to determine the need for a data change notification. The following pseudo code shows how the deadband
            // is calculated:
            //      DataChange if (absolute value of (last cached value - current value) >
            //                                          (deadbandValue/100.0) * ((high-low) of EURange)))
            //