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Activity 4.1 — Data Structures with Array

Introduction

Activity 4.1

Data Structures with Arrays

Why Arrays Exist

Storing 10 related values as separate variables is annoying.
Storing 30+ values becomes hard to manage and easy to mess up.
Arrays store many related values under one variable name.

Vocabulary

Array: a collection of values stored together
Element: one value inside the array
Index: the position number of an element
Zero-based indexing: first element is at index 0

Today's Skills

Create an array using [ ]
Access elements using array[index]
Update an element with assignment

'F' → Fullscreen

Objectives

Create arrays that store multiple related values.
Access elements using indexes (starting at 0).
Modify array elements by assigning a new value.

Activity Tasks

Create a new project named 4-1-arrays.js.
Complete each task individually.
If you get stuck, use the figures as examples and ask for help early.

Figures: Examples

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// Arrays store a collection of related values under one variable name.
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let scores = [84, 91, 76, 88, 95];
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// Elements are accessed by index (position).
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// Indexes start at 0.
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console.log(scores[0]); // first element
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console.log(scores[2]); // third element

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// Updating an element
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let scores = [84, 91, 76, 88, 95];
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// Change the second score (index 1) to 100
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scores[1] = 100;
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console.log(scores);

Task 1: Create + Access

Create an array of strings and print specific elements.
Answer the last-index question as a comment.

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// Task 1 — Create and Access Arrays
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// Follow the steps below.
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// 1) Create an array named 'foods' with 5 food strings.
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let foods = ["pizza", "tacos", "sushi", "pasta", "burgers"];
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// 2) Print the FIRST food (index 0).
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console.log("First food:", foods[0]);
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// 3) Print the THIRD food (index 2).
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console.log("Third food:", foods[2]);
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// 4) Print the LAST food.
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// (Hint: for today, you may use the last index directly since you know there are 5 items.)
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console.log("Last food:", foods[4]);
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// 5) Answer (in a comment):
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// If foods has 5 elements, what is the last index? Why?

Task 2: Modify + Mini Challenge

Update elements by index, then print the updated array.
Mini challenge: compute a range using Math.max and Math.min.

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// Task 2 — Modify an Array + Mini Challenge
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let temps = [72, 68, 75, 70, 69];
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// 1) Print the temperature at index 3 with a label.
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console.log("Temp at index 3:", temps[3]);
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// 2) Update the FIRST temperature to 74.
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temps[0] = 74;
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// 3) Update the LAST temperature to 71.
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temps[4] = 71;
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// 4) Print the entire temps array so we can see the changes.
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console.log("Updated temps:", temps);
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// 5) Mini Challenge (no loops):
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// Create a variable named 'range' that equals highest - lowest.
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// Use ONLY index access (temps[?]) and Math.max/Math.min.
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// Then print: "Range: X"
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//
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// Hint: Math.max(temps[0], temps[1], temps[2], temps[3], temps[4])
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// Hint: Math.min(temps[0], temps[1], temps[2], temps[3], temps[4])

Sample Output

Your program output should something similar to the sample output below.

First food: pizza
Third food: sushi
Last food: burgers
Temp at index 3: 70
Updated temps: [74, 68, 75, 70, 71]
Range: 7

Reflection Questions

You may write your reflection answers as comments at the bottom of your code.

What is an index? What is an element?
Why do arrays start at index 0 (zero-based indexing)?
Explain one reason arrays are easier to manage than 30 separate variables.

Submission

Submit your activity and reflection answers to the appropriate dropbox.