Respond to form events
See this course’s project requirements
A keyboard-usable local workshop calculator with clear validation, correct totals, and an eight-case test record.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- Two-input state trace.
- Deliberate type conversion and blank handling.
- Isolated tested calculation.
- Shared submit handler for pointer and keyboard.
- Clear feedback and eight-case test record.
Review and revise
Use these criteria to check your work and choose what to improve.
- Totals match the stated rule.
- Invalid input never shows a current total.
- Keyboard and pointer paths work consistently.
- Tests and limitations are accurately reported.
Want more background?
The idea in everyday life
Make a small fictional workshop calculator respond reliably to user input.
Listen to the user’s intended action, not only one input device.
Respond to form events — guided practice
Use one submit handler for pointer and keyboard activation.
Save workshop-calculator.html and open it locally in a browser; open the same file in a text editor. It is a complete original worked program. The rule is 8 units per seat, 1–6 whole seats, plus one optional 5-unit group pack. Nothing is sent or bought. Restore the supplied file before each lesson’s code variation.
1. Use the keyboard
Reload, focus seats, enter 3 and press Enter.
You should see: The result is 24 without leaving the page.
A form submit event covers keyboard submission.
2. Use the button
Set 3 seats and click Calculate.
You should see: The same result is 24.
Both paths use the same logic.
3. Inspect the listener
Find addEventListener("submit",handleSubmit) and event.preventDefault().
You should see: The handler prevents the form’s default navigation.
The local calculator updates the current page.
4. Count handlers
Confirm the source registers one submit listener and has no separate click calculation.
You should see: One action triggers one calculation path.
Duplicated handlers can create inconsistent or double effects.
What to finish
A pointer/keyboard interaction record.
Watch for this
Binding only a mouse click while forgetting form submission through Enter.
How can I tell I understand it?
Complete the changed case, explain your result, and pass the three application checks.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
You’ll get an explanation for each answer. Signed in? Your results save to your account.
Pass the check. We’ll save the progress.
Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
Go to the knowledge checkOptional course overview video · same video as Lesson 1
JavaScript DOM Crash Course - Part 1
From Traversy Media. Watch here or open it on YouTube .
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Sources and further reading
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Source & access notes · checked 2026-09-12
Opened and inspected on 2026-09-12: Listeners and event objects.
Access: Free public web page; no paid enrollment required.
Reuse: Public reference; link only. LifeStarter prose, exercises and files are independently authored.
Source & access notes · checked 2026-09-12
Opened and inspected on 2026-09-12: Input constraints and useful errors.
Access: Free public web page; no paid enrollment required.
Reuse: Public reference; link only. LifeStarter prose, exercises and files are independently authored.
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