node module.export and recursion

Question

我正在开发一个节点应用程序，它本质上是一个简单的AWS SQS轮询器，应该坐在不同的队列中侦听新项目。

这是我的module.export:

module.exports = {
    readMessage: function(qParams, qType, tableName) {
        logger.debug(qType);
        SQS.receiveMessage(qParams, handleSqsResponse);
        function handleSqsResponse (err, data) {
            if(err) logger.error("handleSqsResponse error:" + err);
            if (data && data.Messages) {
                data.Messages.forEach(processMessage)
                readMessage(); // continue reading until draining the queue (or UPTIME reached)
            }
            else{
                logger.debug("no data in sqs.");
                // process.exit();
            }
        }
        // 'processing' is mainly writing to logs using winston. Could add here any transformations and transmission to remote systems
        function processMessage(sqsMessage){
            // Parse sqs messag
            var msgObj = JSON.parse(sqsMessage.Body);
            // Process
            logger.info(msgObj.Message);
            _.extend(qParams, { "ReceiptHandle": sqsMessage.ReceiptHandle });
            dbMap[qType](msgObj, qParams, tableName);
        }
    }
}

我遇到的问题是当我尝试再次调用readMessage();时。我得到了ReferenceError: readMessage is not defined 的错误

Answer 1

module.exports是一个普通对象，它暴露给具有方法readMessage的外部模块。readMessage()应该是module.exports.readMessage()。

此外，我建议创建一个变量，然后导出：

var obj = {
    readMessage: function(qParams, qType, tableName) {
        logger.debug(qType);
        SQS.receiveMessage(qParams, handleSqsResponse);
        function handleSqsResponse (err, data) {
            if(err) logger.error("handleSqsResponse error:" + err);
            if (data && data.Messages) {
                data.Messages.forEach(processMessage)
                obj.readMessage(); // continue reading until draining the queue (or UPTIME reached)
            }
            else{
                logger.debug("no data in sqs.");
                // process.exit();
            }
        }
        // 'processing' is mainly writing to logs using winston. Could add here any transformations and transmission to remote systems
        function processMessage(sqsMessage){
            // Parse sqs messag
            var msgObj = JSON.parse(sqsMessage.Body);
            // Process
            logger.info(msgObj.Message);
            _.extend(qParams, { "ReceiptHandle": sqsMessage.ReceiptHandle });
            dbMap[qType](msgObj, qParams, tableName);
        }
    }
}
module.exports = obj;

请注意，我只回答了你特别提出的问题。我没有考虑任何与代码相关的体系结构问题。

Answer 2

function functionName(has = false){
  var total = 0;
  if(has){
    functionName(true)
  } else {
    // Todo
  }
}
module.exports.functionName = functionName;