Logging with structured formats in Node.js - Mini Project: Build & Apply

Logging with structured formats

📖 Scenario: You are building a simple Node.js application that logs user actions. To make logs easy to read and analyze, you will use structured JSON format for logging.

🎯 Goal: Create a Node.js script that logs user actions as JSON objects with clear keys for user, action, and timestamp.

📋 What You'll Learn

Create an object representing a user action with keys user, action, and timestamp

Add a configuration variable for the current time in ISO format

Use a function to create a structured log object combining user, action, and timestamp

Print the structured log as a JSON string

💡 Why This Matters

🌍 Real World

Structured logging helps teams quickly find and analyze logs in production systems, improving troubleshooting and monitoring.

💼 Career

Understanding structured logging is essential for DevOps roles to maintain reliable and observable applications.

1

Create the user action object

Create a constant object called userAction with these exact keys and values: user set to "alice", action set to "login", and timestamp set to an empty string "".

Node.js

# Create the userAction object with keys user, action, and timestamp
# Your code here

Need a hint?

Use const userAction = { user: "alice", action: "login", timestamp: "" };

2

Add current timestamp configuration

Create a constant called currentTime and set it to the current date and time in ISO string format using new Date().toISOString().

Node.js

const userAction = {
  user: "alice",
  action: "login",
  timestamp: ""
};

# Create currentTime with current ISO timestamp
# Your code here

Need a hint?

Use const currentTime = new Date().toISOString(); to get the current time in ISO format.

3

Create a function to build structured log

Write a function called buildLog that takes user, action, and timestamp as parameters and returns an object with these keys and values. Then update userAction.timestamp by calling buildLog with userAction.user, userAction.action, and currentTime, and assign the returned object's timestamp to userAction.timestamp.

Node.js

const userAction = {
  user: "alice",
  action: "login",
  timestamp: ""
};

const currentTime = new Date().toISOString();

# Write buildLog function and update userAction.timestamp
# Your code here

Need a hint?

Define buildLog to return an object with keys user, action, and timestamp. Then update userAction.timestamp using this function.

4

Print the structured log as JSON

Use console.log to print the userAction object as a JSON string using JSON.stringify(userAction).

Node.js

const userAction = {
  user: "alice",
  action: "login",
  timestamp: ""
};

const currentTime = new Date().toISOString();

function buildLog(user, action, timestamp) {
  return { user, action, timestamp };
}

userAction.timestamp = buildLog(userAction.user, userAction.action, currentTime).timestamp;

# Print userAction as JSON string
# Your code here

Need a hint?

Use console.log(JSON.stringify(userAction)) to print the object as JSON.