JavaScript basics — HTML and CSS for kids

Code tip

Line by line — “track each variable as the code runs from top to bottom”

1. let x = 5; makes a variable x holding 5; x = x + 2; changes it to 7.
2. console.log(…) writes in the console; alert(…) shows a pop-up box.
3. Text in quotes + anything = joined text: "5" + 3 → "53".

Use it for: Your first JavaScript, adding a message or a score to a page.

Worked example: ⚡ What does this code print? (Look at the quotes!)
let x = "5";
let y = 3;
console.log(x + y); → 53

✏️ Practice

Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.

🏁 Lesson 25 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 💻 Console Coder badge when you pass — and a certificate when you finish all 10 lessons of Part 3 · Web Development. You can still take the test without signing in.

🖨️ JavaScript Worksheet: Basics

• Worksheet set 1 (PDF)
• Worksheet set 2 (PDF)
• Worksheet set 3 (PDF)