Adaptive skill practice — find your level, get sharper.

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Web Development

Web Development practice

CORS

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Your page's fetch() to another domain hits a CORS error. Where does the fix belong?

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No signup · first signal after 5 answers · your score at session end

How the web works, end to end

The full-stack web fundamentals interviews assume — HTTP methods, status codes and idempotency, REST vs GraphQL, the browser (DOM, events and delegation, storage, the critical rendering path, reflow vs repaint), web security (XSS, CSRF, CORS, the same-origin policy, CSP, cookies, JWT vs sessions), and performance and accessibility (semantic HTML, alt text, code splitting, compression, HTTP/2). Part of the Developer track.

• Meets you at your level — never too easy, never too hard.

• Adapts every question to how you’re doing.

• Tracks your level over time. Skill practice, not a test.

New here? Read the Web Development guide

A free 16-minute primer — the mental model, the mistakes beginners make, and what to practice first.

Curriculum

133 concepts across 21 chapters, from foundations through advanced practice — each one a concept the adaptive question bank can teach and test.

A. URLs, origins and what "same site" means

B. HTTP from the client: methods and the message model

C. Status codes and redirects

D. Headers, caching and content negotiation

E. Cookies and their attributes

F. Same-origin policy, CORS and cross-origin access

G. The document: metadata, head and SEO-relevant markup

H. HTML semantics and content structure

I. Forms and constraint validation

J. The DOM tree and manipulating it

K. The event model: phases, delegation and custom events

L. Loading, rendering and the page lifecycle

M. Links, navigation and history

N. Fetch and talking to a server from script

O. Client-side storage

P. Service workers and PWA basics

Q. Web Components and the shadow DOM

R. Images, media and responsive markup

S. Observers, workers and other platform APIs

T. HTTPS, CSP and the browser's security surface

U. Devtools and reasoning about a live page

View the full curriculum →

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