Output formatting basics in Javascript - Mini Project: Build & Apply

Output formatting basics

📖 Scenario: You are creating a simple program to display product prices in a friendly way for a small shop.

🎯 Goal: Learn how to format output text using template literals to show product names and prices clearly.

📋 What You'll Learn

Create a dictionary (object) with product names and prices

Create a variable for currency symbol

Use a for...in loop to format each product's output

Print the formatted output lines

💡 Why This Matters

🌍 Real World

Formatting output is important for making data easy to read in reports, invoices, or user interfaces.

💼 Career

Many jobs require displaying data clearly, especially in web development and software that shows prices or lists.

1

Create the products object

Create an object called products with these exact entries: "apple": 0.5, "banana": 0.3, "cherry": 0.2

Javascript

// Create the products object with prices
// Your code here

Hint

Use curly braces {} to create an object with keys and values.

2

Add a currency symbol variable

Create a variable called currency and set it to the string "$"

Javascript

const products = {"apple": 0.5, "banana": 0.3, "cherry": 0.2};
// Create the currency variable
// Your code here

Hint

Use const to create a variable that does not change.

3

Format the output lines

Use a for...in loop with variable product to go through products. Inside the loop, create a variable called line that uses a template literal to format the text as "Product: [product], Price: [currency][price]"

Javascript

const products = {"apple": 0.5, "banana": 0.3, "cherry": 0.2};
const currency = "$";
// Use for...in loop to create formatted lines
// Your code here

Hint

Use backticks ` to create a template literal and insert variables with ${}.

4

Print the formatted output

Inside the for...in loop, add a console.log(line) statement to print each formatted line

Javascript

const products = {"apple": 0.5, "banana": 0.3, "cherry": 0.2};
const currency = "$";
for (const product in products) {
    const line = `Product: ${product}, Price: ${currency}${products[product]}`;
    // Print the line
    // Your code here
}

Hint

Use console.log() to show output in the console.

Practice

1. What is the correct way to include a variable name inside a string using template literals in JavaScript?

easy

A. console.log(`Hello, ${name}!`);

B. console.log('Hello, ' + name + '!');

C. console.log("Hello, ${name}!");

D. console.log('Hello, ${name}!');

Solution

1. Step 1: Understand template literals syntax

   Template literals use backticks (`) and ${} to insert variables inside strings.

2. Step 2: Identify correct usage

   console.log(`Hello, ${name}!`); uses backticks and ${name} correctly to embed the variable.

3. Final Answer:

   console.log(`Hello, ${name}!`); -> Option A

4. Quick Check:

   Backticks + ${} = correct template literal [OK]

Hint: Use backticks and ${variable} for easy variable insertion [OK]

Common Mistakes:

• Using quotes instead of backticks for template literals
• Forgetting ${} around variable
• Using single or double quotes with ${} which won't interpolate

2. Which of the following is the correct syntax to print the number 5 and the word 'apples' in one line using template literals?

easy

A. console.log(`5 apples`);

B. console.log(`5 + apples`);

C. console.log('5 apples');

D. console.log(`5 ${apples}`);

Solution

1. Step 1: Check the use of template literals

   Backticks allow strings with variables inside ${}, but here no variable is needed.

2. Step 2: Identify correct string

   console.log(`5 apples`); correctly uses backticks with plain text '5 apples'.

3. Final Answer:

   console.log(`5 apples`); -> Option A

4. Quick Check:

   Backticks with plain text = valid string [OK]

Hint: Use backticks for strings even without variables [OK]

Common Mistakes:

• Using quotes instead of backticks when template literals expected
• Trying to insert undefined variable apples
• Adding plus sign inside template literal as text

3. What will be the output of the following code?

const count = 3;
console.log(`You have ${count} new messages.`);

medium

A. You have ${count} new messages.

B. You have count new messages.

C. You have 3 new messages.

D. SyntaxError

Solution

1. Step 1: Understand template literal variable insertion

   The variable count inside ${} is replaced by its value 3.

2. Step 2: Evaluate the console.log output

   The string becomes 'You have 3 new messages.' and prints exactly that.

3. Final Answer:

   You have 3 new messages. -> Option C

4. Quick Check:

   Variable inside ${} = replaced by value [OK]

Hint: Variables inside ${} show their value in template strings [OK]

Common Mistakes:

• Thinking ${count} prints literally
• Confusing quotes and backticks
• Expecting variable name instead of value

4. Find the error in this code snippet:

let user = 'Anna';
console.log('Welcome, ${user}!');

medium

A. Missing semicolon after let declaration

B. Single quotes do not allow variable interpolation

C. Variable user is not declared

D. Backticks are missing around the string

Solution

1. Step 1: Check string quotes for interpolation

   Single quotes ('') do not process ${} as variable placeholders.

2. Step 2: Identify correct string type for template literals

   Backticks (`) are needed to enable variable interpolation.

3. Final Answer:

   Single quotes do not allow variable interpolation -> Option B

4. Quick Check:

   Use backticks for ${} interpolation [OK]

Hint: Use backticks, not single quotes, for ${} variables [OK]

Common Mistakes:

• Thinking single quotes support ${} interpolation
• Ignoring missing backticks
• Assuming variable is undeclared

5. You want to print a message showing a user's name and age using template literals. The variables are name = 'Sam' and age = 25. Which code correctly formats the output as:
Hello, Sam! You are 25 years old.

hard

A. console.log(`Hello, ${name}! You are age years old.`);

B. console.log('Hello, ' + name + '! You are ' + age + ' years old.');

C. console.log(`Hello, name! You are age years old.`);

D. console.log(`Hello, ${name}! You are ${age} years old.`);

Solution

1. Step 1: Use template literals with variables

   Backticks and ${} allow embedding variables name and age inside the string.

2. Step 2: Check each option for correct variable usage

   console.log(`Hello, ${name}! You are ${age} years old.`); correctly uses ${name} and ${age} to insert values.

3. Final Answer:

   console.log(`Hello, ${name}! You are ${age} years old.`); -> Option D

4. Quick Check:

   Backticks + ${var} for each variable = correct [OK]

Hint: Use ${variable} inside backticks for multiple variables [OK]

Common Mistakes:

• Using variable names without ${} inside template literals
• Mixing quotes and backticks incorrectly
• Concatenating strings instead of using template literals