/CS472-Homework-07-Node-Modules

CS472-Homework-07-Node-Modules

Exercise 01

Create a file data.json which contains the following JSON structure:

[{"id": "tfHxMIRS-g7pX1rRLVzm0", "name": "Asaad Saad"}, {"id": "YdjFznHRgOi_UzYbXbLO0", "name": "Theo Saad"}]
  • Create a class Names, once instantiated, it reads the JSON file synchronously, and assigns its content to a private property data.
  • Create a method persist() to write back the instance property data back into the data.json file, and emit an event data_saved to confirm that the file is written successfully.
  • Create a method addName(name: string) to add a new name object to data, generate a new id using nanoid package, then persist the data changes to the hard drive in data.json.
  • Create a method getNames() to return all names from data.
  • Create a method getNameById(id: string) to return the name of the provided id.
  • Create a method updateNameById(id: string, new_name: string) to update the name property of the provided id from data, then persist the changes to the hard drive in data.json.
  • Create a method deleteNameById(id: string) to remove the name object of the given id from data, then persist the changes to the hard drive in data.json.

Test your code:

  • create an instance of Names class.
  • listen to data_saved event, and print a message Data has been saved to data.json successfully.
  • call all the methods and test.

Exercise 02

Create an asynchronous function checkSystem() that returns a promise and checks if the OS memory size is at least 8 GB and the processor has at least 4 cores (use os core module, which has the following methods: cpus() and totalmem()).

  • If the system doesn't have enough memory we should reject with a message: You need at least 8 GB of RAM
  • If the system doesn't have at least 4 cores, reject with this message: Processor must have at least 4 cores
  • If the system has enough specs, resolve with the following message System is checked successfully.

Note: 1 KB is 1024 bytes, 1 MB is 1024 KB, 1 GB is 1024 MB.

Exercise 03

  • Create a folder /input and place 10 high-resolution photos from Pexels.
  • Create an empty folder /output.
  • Read Node documentation to learn about working with folders in Node using the fs core module.
  • Write a script read the images' name in both the /input and /output folders, and determine the difference between them (files that exist in /input but does not exist in /output).
  • If an image exists in /input and does not exist in /output, use Sharp to resize the source image to a thumbnail size of 200 width, and save the thumbnail image in the /output folder.
  • Use Node Cron to schedule a cron job using the following step value */30 * * * * * that runs your script every 30 seconds.

Remember to install the definately typed (DT) package as a development dependency if the package does not provide types.

Exercise 04

Environment variables hold secret keys and sensitive configuration data that we prefer to keep in a safe place. They are usually accessed from the process.env global object.

Update the previous exercise to send you an email with the following body:

From: Thumbnail Generator App
Subject: Status Report
Body: 
This is an automated email. 
The input folder has 31 thumbnails.
The output folder has 31 thumbnails.
Generated 0 new thumbnails.

Use the dotenv module to save environment variables.
Use the @sendgrid/mail module and integrate it with your application to send the status email.