Documentation and Examples on Server-Side Scripting

Ok thanks guys I solved this eventually.

if (event.response.record) {
    _.each(event.response.record, function (record, index, list) {
        _.each(record.wp_postmetas_by_post_id, function (record, index, list) {
        
            if (record.meta_key == "_end_ts"){
                record.endseconds = record.meta_value;
            }
            if (record.meta_key == "_start_ts"){
                record.startseconds = record.meta_value;
            }
        });    
    });
}

Jason.