Finally block in Javascript - Mini Project: Build & Apply

Using the Finally Block in JavaScript

📖 Scenario: Imagine you are writing a program that tries to read a file and process its content. Sometimes the file might not exist, causing an error. You want to make sure that no matter what happens, a message is always shown to say the process is finished.

🎯 Goal: You will create a simple program that uses a try, catch, and finally block. The finally block will always run, whether an error happens or not.

📋 What You'll Learn

Create a variable called fileContent with the value "Hello, world!".

Create a variable called fileExists and set it to false.

Write a try block that throws an error if fileExists is false.

Write a catch block that catches the error and sets fileContent to "Default content".

Write a finally block that prints "Process finished.".

Print the value of fileContent after the try-catch-finally.

💡 Why This Matters

🌍 Real World

In real programs, you often need to handle errors like missing files or network problems. The <code>finally</code> block helps you make sure some code always runs, like closing files or showing messages.

💼 Career

Understanding error handling with <code>try-catch-finally</code> is important for writing reliable JavaScript code in jobs like web development, backend programming, and software testing.

1

Create initial variables

Create a variable called fileContent and set it to the string "Hello, world!".

Javascript

// Create a variable called fileContent and set it to "Hello, world!"
// Your code here

Need a hint?

Use let fileContent = "Hello, world!"; to create the variable.

2

Add a file existence flag

Create a variable called fileExists and set it to false.

Javascript

let fileContent = "Hello, world!";
// Create a variable called fileExists and set it to false
// Your code here

Need a hint?

Use let fileExists = false; to create the flag.

3

Write try-catch-finally blocks

Write a try block that throws an error with the message "File not found" if fileExists is false. Then write a catch block that sets fileContent to "Default content". Finally, write a finally block that prints "Process finished.".

Javascript

let fileContent = "Hello, world!";
let fileExists = false;

// Write try-catch-finally blocks as described
// Your code here

Need a hint?

Use try, catch, and finally blocks exactly as described.

4

Print the file content

Write a line to print the value of fileContent after the try-catch-finally block.

Javascript

let fileContent = "Hello, world!";
let fileExists = false;

try {
    if (!fileExists) {
        throw new Error("File not found");
    }
} catch (error) {
    fileContent = "Default content";
} finally {
    console.log("Process finished.");
}

// Print the value of fileContent
// Your code here

Need a hint?

Use console.log(fileContent); to print the content.