worker.js

# worker.js
exports.handler = async function(event) {  
  const failedMessageIds = [];  
  
  event.Records.forEach(record => {    
    try {      
      const bodyData = JSON.parse(record.body);      
      console.log(`Processing ${record.messageId}`);      
      // ...    
    } catch (e) {      
    	failedMessageIds.push(record.messageId);    
    }  
  });
  
  return {    
    batchItemFailures: failedMessageIds.map(id => {      
      return {        
        itemIdentifier: id      
      }    
    })  
  }
}