/**
     * This function attempts to disable an item sublist field through SuiteScript API, and disables the field
     * through the DOM if that fails.
     *
     * @param rec {N/currentRecord.CurrentRecord}
     * @param fieldId {String} Internal id of a column field
     * @return {void}
     */
    function disableSublistField(rec, fieldId) {

        /* {Number} The current item index */
        var line = rec.getCurrentSublistIndex({sublistId: 'item'});

        try {
            /* {N/record.Field} */
            var field = rec.getSublistField({sublistId: 'item', fieldId: fieldId, line: line});

            field.isDisabled = true;

        } catch (e) {

            /*
             * The getSublistField method will throw an error if the line has not yet been committed, so we have
             * to disable the field through the DOM and let a validateField function guard it from edit.
             */
            jQuery("input[name=inpt_" + fieldId + "]").prop('disabled', true); //For select fields
            jQuery("input[name=" + fieldId + "_formattedValue]").prop('disabled', true); // For text/number fields
        }
}