Unit 8.3 – Iteration: Movie Ticket Price Calculator 🎬

Overview

In this project, you will write a JavaScript program that calculates movie ticket prices based on the user’s age.
You will use iteration and conditional logic to determine which price category applies and display the result on the webpage.

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Learning Goals

By the end of this lesson, you should be able to:

• Use variables and conditional logic to implement decision-making in JavaScript.
• Capture user input from a text field using document.getElementById().
• Update the DOM dynamically to display results.
• Understand basic iteration concepts through repetitive checking and validation.

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Instructions

1. Create your HTML file

Include the following elements in your index.html:

<input id="age" type="number" placeholder="Enter your age">
<button onclick="calculate()">Check Ticket Price</button>
<p id="priceOutput"></p>

2. Create your JavaScript file (script.js)

Your code should define a function named calculate() that reads the age from the input, determines the correct ticket price, and displays it.

function calculate() {
  // your code here
}

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Ticket Price Rules

Age Range	Ticket Type	Price
0–12	Child	$7
13–17	Student	$12
18–64	Adult	$20
65+	Senior	$12

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How It Works

1. The user enters their age in the input field.
2. When the button is clicked, your program calls the calculate() function.
3. The function checks the input against the price ranges and prints the correct ticket price inside the <p id="priceOutput"></p> element.

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Assessment Criteria

Criteria	Description	Points
HTML Setup	Includes input with id="age" and output element with id="priceOutput"	20
JS Functionality	Implements calculate() correctly using conditional statements	40
Output Accuracy	Displays correct prices for all age groups	30
Code Clarity	Proper indentation, comments, and readability	10

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Common Mistakes

1. Forgetting to convert the input value to a number using Number().
2. Not assigning id attributes correctly in HTML.
3. Printing output to the console instead of the webpage.
4. Missing calculate() definition or incorrect function name.

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Example Output

Input (Age)	Expected Output
5	$7
15	$12
35	$20
70	$12

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Unit Connection

• Unit 8.3 – Iteration introduces using loops and conditions to automate repetitive logic.
• This lab focuses on using if–else structures to apply different rules for different input cases.
• This lays the groundwork for more complex iteration problems, such as validating multiple inputs or processing lists of data.

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Submission

Commit and push your work to your assigned GitHub Classroom repository.
Your instructor’s autograder will test your project automatically.