Make a read-only request and inspect status
See this course’s project requirements
A tested local API-response viewer with a request contract, validation rules, six response cases and an honest integration handoff.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- Request/response contract with limits.
- Type and status observations.
- Working local viewer.
- Explicit empty/error/validation behavior.
- Six-case test matrix and README.
Review and revise
Use these criteria to check your work and choose what to improve.
- Fields and types are understood.
- Failures do not show stale results.
- All six cases behave as described.
- Simulation and live-integration limits are explicit.
Want more background?
The idea in everyday life
Build a read-only viewer for a fictional library-hours API contract.
Await pauses this function until its promise settles; it does not validate the response.
Make a read-only request and inspect status — guided practice
Use an asynchronous response and explain simulation versus live transport.
Save api-viewer.html from the download and open it in a modern browser. Open its source in a text editor. The complete original file supplies every fixture and function. It simulates GET /hours locally; it does not contact a real library. Reload after edits; restore the supplied file before each lesson unless told otherwise.
1. Trace the call
Find await mockRequest in loadHours and read the three arguments.
You should see: It passes /hours, GET and the chosen case.
The adapter replaces transport while preserving a response-processing exercise.
2. Inspect successful status
Run success and read the trace beneath the list.
You should see: GET /hours -> 200.
Status is separate from body content.
3. Try an unsupported path
In source change only the call path to /unknown, save and reload. Click Load hours.
You should see: The trace shows 404 and no branch list.
The adapter checks the contract before returning a successful body.
4. Restore
Change the path back to /hours. Record that live code would call fetch against an authorized endpoint and follow its CORS/authentication rules.
You should see: Success returns again; the project remains an honest local simulation.
No credential or cross-origin workaround is part of this exercise.
What to finish
A traced request with one deliberate path failure.
Watch for this
Saying the simulator contacted a real service or tested real network availability.
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
APIs for Beginners - How to use an API (Full Course / Tutorial)
From freeCodeCamp.org. Watch here or open it on YouTube .
Optional course overview. Follow the written steps below at your own pace.Tools, templates, and lesson sources
Tools and templates
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Sources and further reading
Explore the references behind this lesson.
Source & access notes · checked 2026-09-12
Opened and inspected on 2026-09-12: Responses, promises and explicit HTTP status checks.
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: 200, 404 and server-error categories.
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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