问lambda nodejs错误index.handler未定义或未导出

EN

audit_package
 - nodejs
    - node.js

console.log('function starts');

const AWS = require('aws-sdk');
const docClient = new AWS.DynamoDB.DocumentClient({region: 'us-west-2'});

exports.handler = function(event, context, callback){
    console.log('processing event: %j', event);

    let scanningParameters = {
        TableName: 'epro-audit-cert',
        Limit: 10 //maximum result of 100 items
    };

    //In dynamoDB scan looks through your entire table and fetches all data
    docClient.scan(scanningParameters, function(err,data){
        if(err){
            callback(err, null);
        }else{
            callback(null,data);
        }
    });