= Cheatsheet Node.js =

**Summary**: Nodejs hints, tips, oneliners and best practices. \\
**Date**: 8 December 2024 \\
{{tag>cheatsheet nodejs}}

= AWS Lambda Node.js =

== Get Dynamo DB Table as Log ==

<code javascript>
const AWS = require("aws-sdk");
const dynamodb = new AWS.DynamoDB();

// Get Time in the Netherlands
var dutchTime = new Date().toLocaleString('en-US', {timeZone: "Europe/Amsterdam"});
var requestTime = new Date(dutchTime);
var year = requestTime.getFullYear();
var month = requestTime.getMonth() + 1; //Months go from 0 - 11
// Set months to get logs for
if (month === 1){
    var fullMonth = year + "-0" + month;
    var lastMonth = (year - 1 ) + "-12";
}
if (month > 1 && month < 10){
    var fullMonth = year + "-0" + month;
    var lastMonth = year + "-0" + (month - 1);
}
if (month === 10){
    var fullMonth = year + "-" + month;
    var lastMonth = year + "-0" + (month - 1);
}
if (month > 10){
    var fullMonth = year + "-" + month;
    var lastMonth = year + "-" + (month - 1);
}

const params = {
  TableName: 'LogTable',
  FilterExpression: 'begins_with(RequestTime, :RequestTime) OR begins_with(RequestTime, :RequestTime2)',
  ExpressionAttributeValues: {
    ':RequestTime': {S: fullMonth},
    ':RequestTime2': {S: lastMonth},
  },
};

exports.handler = (event, context, callback) => {
    console.log(fullMonth + lastMonth);
    dynamodb.scan(params, (err, data) => {
        if(err){
            console.log('Error on retrieving log data ' + err);
        }
        callback(null, data['Items']);
    });
};
</code>

== Send Email ==

<code javascript>
//jshint esversion:6

/* IAM-Access
Description: Sends the end email to the customer with all required information.

Links:
- AWS Javascript SDK for SES: https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/SES.html
- Util.inspect and JSON.stringify: https://medium.com/@reginald.johnson/testing-aws-lambda-functions-the-easy-way-41cf1ed8c090

*/

// AWS Variables
var aws = require('aws-sdk');
aws.config.update({region: 'eu-west-1'});
// SES const & vars
const ses = new aws.SES();
var util = require('util');
var emailfrom = 'info@shiftwiki . nl';

// Workflow Variables
// Declaring the customerData variable
var customerData;

// Send email to customer
function sendMail(params){
  console.log("Start function sendMail. Email address: " + params.email );
  if (customerData.discountCode === "testmodus"){
    emailto = 'sjoerd@shiftwiki .nl';
    emailfrom = 'info@shiftwiki .nl';
  } else {
    emailto = params.email;
  }
  console.log("Email address: " + emailto );
  //email
  var mailparams = {
      Destination: {
          ToAddresses: [emailto]
      },
      Message: {
          Body: {
              Html: {
                  Charset: "UTF-8",
                  Data: "Dear " + params.firstname + " " + params.lastname +
                  "<br><br>" +
                  "All is ready. " +
                  "<br><br>" +
                  "Kind regards, <br>" +
                  "Shift"
              }
          },
          Subject: { Data: "[SHIFT]Ready. "}
      },
      Source: emailfrom
  };
  return ses.sendEmail(mailparams).promise();
}

// Error Handling
function errorResponse(message) {
  this.name = "email-to-customer-end";
  this.message = message;
}
errorResponse.prototype = new Error();

exports.handler = (event, context, callback) => {
    console.log("Start email-to-customer-end");
    //console.log(event);
    //console.log(context);
    customerData = event;

    // Display available information
    console.log(customerData);

    // Invoke function sendmail
    sendMail(customerData).then(() => {
      customerData.status = customerData.status + "Customer end email sent out. ";
      callback(null, customerData);
    }).catch((err) => {
      // Error to CloudWatch
      console.error(err);
      // Add Error to Task Output
      const error = new errorResponse(err.message);
      callback(error);
    });
};
</code>

== Create S3 Bucket ==

<code javascript>
//jshint esversion:6

/* S3-Buckets-Add
Description: Creates two S3 buckets, configure access policy, website hosting and redirect.

Original PowerShell Script:
### S3 Bucket Creation as a Static Website ###
New-S3Bucket -BucketName $bucketname -PublicReadOnly
Write-S3BucketWebsite -BucketName $bucketname -WebsiteConfiguration_IndexDocumentSuffix index.html -WebsiteConfiguration_ErrorDocument error.html
$s3policy = '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":"*","Action":"s3:GetObject","Resource":"arn:aws:s3:::bucketnameplaceholder/*"}]}'
$s3policy = $s3policy -replace "bucketnameplaceholder", "$bucketname"
Write-S3BucketPolicy -BucketName "$bucketname" -Policy $s3policy
write-host "S3 Bucket $bucketname was created on $((Get-S3Bucket -BucketName $bucketname).creationdate) "
### S3 Bucket Creation Redirect ###
New-S3Bucket -BucketName $wwwbucketname
Add-S3PublicAccessBlock -BucketName $wwwbucketname `
-PublicAccessBlockConfiguration_BlockPublicAcl $true `
-PublicAccessBlockConfiguration_BlockPublicPolicy $true `
-PublicAccessBlockConfiguration_IgnorePublicAcl $true `
-PublicAccessBlockConfiguration_RestrictPublicBucket $true
Write-S3BucketWebsite -BucketName $wwwbucketname -RedirectAllRequestsTo_HostName $bucketname
write-host "S3 Bucket $wwwbucketname was created on $((Get-S3Bucket -BucketName $wwwbucketname).creationdate) "

Links:
- AWS Javascript SDK for S3: https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html

*/

// AWS Variables
var aws = require('aws-sdk');
aws.config.update({region: 'eu-west-1'});
var s3 = new aws.S3();

// Workflow Variables
// Declaring the customerData variable
var customerData;

//function s3BucketCreate
function s3BucketCreate(params) {
  console.log("Start function s3BucketCreate. Input: " + params.domainname);
  return s3.createBucket({
    Bucket: params.domainname,
    CreateBucketConfiguration: {
     LocationConstraint: aws.config.region
    },
    ACL: "public-read"
  }).promise();
}

//function s3wwwBucketCreate
function s3wwwBucketCreate(params) {
  console.log("Start function s3wwwBucketCreate. Input: " + params.wwwdomainname);
  return s3.createBucket({
    Bucket: params.wwwdomainname,
    CreateBucketConfiguration: {
     LocationConstraint: aws.config.region
    }
  }).promise();
}

//function s3BucketWebsite
function s3BucketWebsite(params){
  console.log("Start function s3BucketWebsite. Input: " + params.domainname);
  return s3.putBucketWebsite({
    Bucket: params.domainname,
    WebsiteConfiguration: {
      ErrorDocument: {
        Key: 'error.html'
      },
      IndexDocument: {
        Suffix: 'index.html'
      }
    }
  }).promise();
}

//function s3BucketPolicy
function s3BucketPolicy(params){
  console.log("Start function s3BucketPolicy. Input: " + params.domainname);
  var s3policyplaceholder = "{\"Version\":\"2012-10-17\",\"Statement\":[{\"Effect\":\"Allow\",\"Principal\":\"*\",\"Action\":\"s3:GetObject\",\"Resource\":\"arn:aws:s3:::domainnameplaceholder/*\"}]}";
  var s3policy = s3policyplaceholder.replace("domainnameplaceholder", params.domainname);
  return s3.putBucketPolicy({
    Bucket: params.domainname,
    Policy: s3policy,
  }).promise();
}

//function s3BucketPublicAccessBlock
function s3BucketPublicAccessBlock(params){
  console.log("Start function s3BucketPublicAccessBlock. Input: " + params.wwwdomainname);
  return s3.putPublicAccessBlock({
    Bucket: params.wwwdomainname,
    PublicAccessBlockConfiguration: {
      BlockPublicAcls: true,
      BlockPublicPolicy: true,
      IgnorePublicAcls: true,
      RestrictPublicBuckets: true
    }
  }).promise();
}

//function s3BucketWebsiteRedirect
function s3BucketWebsiteRedirect(params){
  console.log("Start function s3BucketWebsiteRedirect. Input: " + params.wwwdomainname + " and " + params.domainname);
  return s3.putBucketWebsite({
    Bucket: params.wwwdomainname,
    WebsiteConfiguration: {
      RedirectAllRequestsTo: {
        HostName: params.domainname
      }
    }
  }).promise();
}

// Error Handling
function errorResponse(message) {
  this.name = "s3-buckets-add";
  this.message = message;
}
errorResponse.prototype = new Error();

exports.handler = (event, context, callback) => {
    console.log("Start s3-buckets-add");
    // console.log(event);
    customerData = event;

    // Display available information
    console.log(customerData);

    // create params variable to pass to s3 functions
    var params = {
      domainname: customerData.domainname,
      wwwdomainname: customerData.wwwdomainname
    };

    // Invoke function s3BucketCreate
    s3BucketCreate(params).then(() => {
      customerData.status = customerData.status + "S3 Bucket creation success. ";
      s3BucketWebsite(params).then(() => {
          customerData.status = customerData.status + "S3 Bucket configured as website. ";
          s3BucketPolicy(params).then(() => {
            customerData.status = customerData.status + "S3 Bucket Policy set. ";
            s3wwwBucketCreate(params).then(() => {
              customerData.status = customerData.status + "S3 wwwBucket creation success. ";
              s3BucketPublicAccessBlock(params).then(() => {
                customerData.status = customerData.status + "S3 wwwBucket public access blocked. ";
                s3BucketWebsiteRedirect(params).then(() => {
                  customerData.status = customerData.status + "S3 wwwBucket redirected to S3 Bucket. ";
                  callback(null, customerData);
                }).catch((err) => {
                  // Error to CloudWatch
                  console.error(err);
                  // Add Error to Task Output
                  const error = new errorResponse(err.message);
                  callback(error);
                });
              }).catch((err) => {
                // Error to CloudWatch
                console.error(err);
                // Add Error to Task Output
                const error = new errorResponse(err.message);
                callback(error);
              });
            }).catch((err) => {
              // Error to CloudWatch
              console.error(err);
              // Add Error to Task Output
              const error = new errorResponse(err.message);
              callback(error);
            });
          }).catch((err) => {
            // Error to CloudWatch
            console.error(err);
            // Add Error to Task Output
            const error = new errorResponse(err.message);
            callback(error);
          });
      }).catch((err) => {
        // Error to CloudWatch
        console.error(err);
        // Add Error to Task Output
        const error = new errorResponse(err.message);
        callback(error);
      });
    }).catch((err) => {
      // Error to CloudWatch
      console.error(err);
      // Add Error to Task Output
      const error = new errorResponse(err.message);
      callback(error);
    });
};
</code>