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JavaScript Intermediate: Write Code That Doesn't Fall Apart When the Data Changes
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JavaScript Intermediate: Write Code That Doesn't Fall Apart When the Data Changes

Final Check: JavaScript Intermediate

Fifteen questions across the whole course, from npm ci to fetch and tests. If you score below 12, go back to the sections where you missed and redo their Check Yourself quizzes.

15 min JavaScriptObject-Oriented ProgrammingAPIs and IntegrationsTesting and DebuggingPackaging and Dependencies Intermediate
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1. A README says "Requires Node 24". node -v shows v18.19.0. What do you do?
Ignore it. JavaScript is backwards compatible. Install the current LTS (or switch with a version manager), open a new terminal and check again. Delete node_modules and reinstall.
2. Which files should be committed to Git?
package.json and package-lock.json package.json and node_modules Only package.json
3. Which command belongs in your CI pipeline?
npm ci npm install -g npm install
4. A file has export default function peso(...). How do you import it?
import peso from "./format.js" const peso = require("./format.js") import { peso } from "./format.js"
5. "SyntaxError: Cannot use import statement outside a module" in the browser. Fix?
Use require() instead. Rename the file to .mjs. Add type="module" to the script tag and serve the page over http://, not file://.
6. What does a getter like get total() give you?
A value that's calculated once and cached forever. A method you call as order.total(). A property that's calculated every time it's read, so it can't go stale.
7. Why use #items instead of _items in a class?
# makes it faster. #items is truly private. Code outside the class can't read or change it. They're the same, # is just shorter.
8. const { status = "pending" } = { status: null }. What is status?
null undefined "pending"
9. Which gives a full copy of plain nested data, dates included?
{ ...data } JSON.parse(JSON.stringify(data)) structuredClone(data)
10. You need units sold per SKU from orders that each have several items. What's usually clearest?
map, because there's one result per order. A for...of loop that adds to an object, maybe after a filter for paid orders. One long reduce with spread on every step.
11. Your server runs in UTC. Which line shows an order time correctly for Manila staff?
new Intl.DateTimeFormat("en-PH", { timeStyle: "short", timeZone: "Asia/Manila" }).format(order.createdAt) order.createdAt.getHours() order.createdAt.toISOString()
12. A promise has been fulfilled. Can it later become rejected?
Only if you call .catch on it. No. Once it's fulfilled or rejected, it stays that way. Yes, if an error happens later.
13. Which code correctly treats a 404 from fetch as an error?
fetch(url).catch(...) const r = await fetch(url); if (!r.ok) throw new Error(`HTTP ${r.status}`); try { await fetch(url) } catch { ... }
14. Your catch block is empty "so the page doesn't crash". What's the problem?
None. Not crashing is always better. Every failure, including bugs, disappears without a trace. Empty catch blocks are a syntax error.
15. You fixed a rounding bug in the discount code. What's the best next step?
Nothing, it's fixed. Write a test that fails with the old code and passes with the fix. Add a comment explaining the fix.

About

Fifteen questions across the whole course, from npm ci to fetch and tests. If you score below 12, go back to the sections where you missed and redo their Check Yourself quizzes.

Duration
15 min
Last update
09/06/2026
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