Computer Science
Grade 8
20 min
JavaScript Fundamentals
JavaScript Fundamentals
What you'll learn
- Identify at least three common HTML tags (e.g., ``, ``, ``) and their functions with 80% accuracy on a worksheet.
- Explain the basic structure of an HTML document, including the `` and `` sections, in their own words with sufficient detail.
- Apply their knowledge to create a simple HTML webpage with a title, a heading, and a paragraph that displays correctly in a web browser.
- Solve common HTML coding errors, such as missing closing tags, in a provided HTML file and successfully render the corrected page in a browser.
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Declare and initialize variables using `let` and `const`.
Identify and use the three primary data types: String, Number, and Boolean.
Write a basic function that accepts parameters and returns a value.
Use `console.log()` to display output and debug simple programs.
Create and access elements in a simple array.
Explain how JavaScript makes web pages interactive.
Ever wondered how a website knows your name or how a simple click can change what you see on a page? 🤔 That's the magic of JavaScript!
In this lesson, you'll learn the basic building blocks of JavaScript, the programming language of the web. We'll explore how to store information, make decisions, and create reusable blocks of code that bring websites to life.
Real-World Applicati...
2
Key Concepts & Vocabulary
TermDefinitionExample
VariableA container for storing data values. In JavaScript, we use `let` for variables that can change and `const` for variables that stay constant.`let score = 100;` or `const playerName = 'Alex';`
Data TypeThe type of data a variable can hold. The most common types are String (text), Number (numeric values), and Boolean (true or false).`'Hello World'` is a String, `42` is a Number, `true` is a Boolean.
FunctionA reusable block of code designed to perform a specific task. Functions can take inputs (called parameters) and can return an output.`function greet(name) { return 'Hello, ' + name; }`
ArrayA special variable that can hold more than one value at a time, stored in an ordered list. Each item in an array has an index, starting from...
3
Core Syntax & Patterns
Variable Declaration Syntax
`let variableName = value;` or `const constantName = value;`
Use `let` when you expect the variable's value to change later in the program. Use `const` for values that should never change, like a player's birth date or a game's title.
Function Definition Syntax
`function functionName(parameter1, parameter2) { // code to run
return result; }`
Use this structure to create a named, reusable block of code. The `return` keyword sends a value back out of the function when it's finished.
String Concatenation
`'string1' + ' ' + variableName`
The plus sign `+` is used to join (concatenate) strings together. It's often used to combine text with the values stored in variables to create dynamic messages....
4 more steps in this tutorial
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Challenging
A programmer writes this code, but nothing appears in the console. What is the most likely reason? `function calculateTotal(base, bonus) { return base + bonus; } let finalScore = calculateTotal(100, 20);`
A.The `console.log()` command was never used to display the result.
B.The function was not called correctly.
C.The variables `base` and `bonus` were not declared.
D.The code has a syntax error and cannot run.
Challenging
Analyze the following two code blocks. Which one will cause an error and why?
Block A: `const teamName = 'Eagles'; teamName = 'Hawks';`
Block B: `let score = 10; score = 20;`
A.Block A, because you cannot reassign a value to a `const` variable.
B.Block B, because you cannot reassign a value to a `let` variable.
C.Both will cause an error.
D.Neither will cause an error.
Challenging
You are given the code: `let values = [10, 'ten', true];`. What are the data types of `values[0]`, `values[1]`, and `values[2]` respectively?
A.Number, Number, Boolean
B.String, String, String
C.Number, String, Boolean
D.Array, Array, Array
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Frequently asked questions
What grade level is "JavaScript Fundamentals"?
JavaScript Fundamentals is a Grade 8 Computer Science lesson on ExcelOS.
What will I learn in JavaScript Fundamentals?
You'll be able to: Identify at least three common HTML tags (e.g., ``, ``, ``) and their functions with 80% accuracy on a worksheet; Explain the basic structure of an HTML document, including the `` and `` sections, in their own words with….
Is "JavaScript Fundamentals" free to practice?
Yes. You can read the tutorial preview for free, and signing up for a free ExcelOS account unlocks the full tutorial and all practice questions with instant feedback.
How many practice questions are included with JavaScript Fundamentals?
This lesson includes 25 practice questions across multiple difficulty levels, each with instant feedback and explanations.