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Project design

Design the skeleton of the beginner final mini app.

Project: Task tracker

In this 5-lesson project you will build a small task tracker app. Each lesson adds one piece; the last lesson gives you a working command line app. The app saves and loads tasks from a file.

First we must define the data file path. In Node.js the path module builds file paths in a cross-platform way. The call path.join("data", "tasks.json") gives the string "data/tasks.json". It uses the right separator on both Linux and Windows. Each lesson's beginning code includes the previous lesson's solution; the app grows step by step.

Using path.join

path.join joins multiple path parts into one path. path.join("data", "tasks.json") gives "data/tasks.json". path.join(__dirname, "tasks.json") gives a full path to the current file's directory.

In this project we will define a constant DATA_FILE: const DATA_FILE = path.join("data", "tasks.json");. We will use this constant in later lessons with fs.writeFileSync and fs.readFileSync to save and load tasks. Keeping the path in one constant makes it easy to change the file name in one place.

Practice Define the DATA_FILE constant

Import the path module with require. Define DATA_FILE with path.join("data", "tasks.json"). Print "Ready" with console.log.

Starter code

index.js
// Import the path module and define the DATA_FILE constant
// write here

console.log("Ready");

Sample solution

index.js
const path = require("path");
const DATA_FILE = path.join("data", "tasks.json");
console.log("Ready");

Expected output

Hazır

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which module builds file paths?

index.js
path.join("data", "tasks.json")
  • const path = require("path") Correct answer
  • const fs = require("fs")
  • const path = require("http")
  • const os = require("os")

Explanation: The path module builds OS-correct paths.

2 Complete the path.join call

Question 
const DATA_FILE = path.join("____", "tasks.json");
Answer 
const DATA_FILE = path.join("data", "tasks.json");

Explanation: 'data' is the folder name.

3 Match each piece to its role

Term Meaning
path Path module
path.join Joins path parts
DATA_FILE Data file path
require Imports a module

All lessons in Beginner

1 Node.js basics

  1. What is Node.js?
  2. Your first program
  3. ES modules
  4. package.json
  5. CommonJS vs ESM
  6. Summary - Node.js basics

2 Variables

  1. let and const
  2. var and scope
  3. Type inference
  4. Destructuring
  5. Spread and rest
  6. Summary - Variables

3 Data types

  1. Primitive types
  2. Template literals
  3. Number and Math
  4. Symbol
  5. typeof
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. process.argv
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Nullish coalescing
  6. Summary - Operators

6 Strings

  1. String methods
  2. String search
  3. substring and slice
  4. replace and split
  5. padStart and trim
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. switch
  4. Ternary
  5. Optional chaining
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. for...of
  4. for...in
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. push and pop
  4. shift and unshift
  5. splice and slice
  6. Summary - Arrays

11 Array methods

  1. map
  2. filter
  3. reduce
  4. find and some
  5. forEach
  6. Summary - Array methods

12 Objects

  1. Object literal
  2. Property access
  3. Computed properties
  4. Object methods
  5. Object spread
  6. Summary - Objects

13 Functions

  1. Defining functions
  2. Return values
  3. Arrow functions
  4. Default parameters
  5. Rest parameters
  6. Summary - Functions

14 Callbacks

  1. What are callbacks?
  2. Higher-order functions
  3. forEach with callbacks
  4. Error-first callbacks
  5. Callback hell
  6. Summary - Callbacks

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Promises

  1. What are promises?
  2. then and catch
  3. Promise.all
  4. Promise.race
  5. finally
  6. Summary - Promises

17 async/await

  1. async function
  2. await
  3. try/catch
  4. await with Promise.all
  5. Sequential await
  6. Summary - async/await

18 fs module

  1. fs.promises
  2. readFile
  3. writeFile
  4. appendFile
  5. existsSync
  6. Summary - fs module

19 path module

  1. path.join
  2. path.resolve
  3. path.parse
  4. path.dirname and basename
  5. path.extname
  6. Summary - path module

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. fs persistence
  5. Putting it together