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JavaScript Core
JavaScript Fundamentals: Values, Scope & Functions
Test the JavaScript rules that shape everyday code: types, coercion, scope, closures, objects, and function behavior.
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Advanced JavaScript
Async JavaScript: Promises, Tasks & the Event Loop
Reason through Promise chains, async functions, timers, error flow, cancellation, and event-loop ordering.
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Browser JavaScript
DOM & Browser JavaScript: Events, Forms & Web APIs
Challenge your understanding of event propagation, DOM updates, forms, selectors, storage, accessibility, and browser behavior.
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JavaScript
JavaScript: Missing Values & Safe Defaults
Distinguish missing data from valid empty values and choose precise defaults.
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JavaScript
JavaScript: Destructuring, Rest & Spread
Reason about extraction, defaults, shallow copies, and object merge order.
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JavaScript
JavaScript: Sorting & Comparator Decisions
Predict ordering, avoid unwanted mutations, and define reliable tie breakers.
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CSS
CSS: Container Query Components
Make reusable components respond to their available space.
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CSS
CSS: Stacking Contexts & Overlays
Explain why overlays hide behind other elements and fix the right layer.
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CSS
CSS Grid: Tracks, Placement & Sizing
Work through flexible tracks, implicit rows, and content-driven overflow.
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Accessibility
Accessibility: Image Alternatives in Context
Choose meaningful text alternatives for icons, charts, links, and decorative images.
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Accessibility
Accessibility: Status Messages & Live Regions
Announce interface updates clearly without overwhelming or moving users.
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Web Development
HTTP: CORS & Browser Request Boundaries
Diagnose cross-origin reads, preflights, credentials, and server policies.
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Web Development
HTTP: Conditional Writes & Edit Conflicts
Prevent lost updates and recover from stale resource versions.
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Development Tools
Git: Undo, Restore & Recovery
Choose the right operation for shared commits, staged changes, and recovery.
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Databases
SQL: Joins, NULL & Aggregation
Predict result rows and counts before trusting a report.
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Google Apps Script
Google Apps Script Fundamentals & Services
Test the runtime, authorization model, built-in services, logging, web apps, and core patterns used in Apps Script projects.
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JavaScript Core
JavaScript Arrays, Objects & Data Transformations
Challenge your understanding of immutable updates, array methods, references, destructuring, Maps, Sets, and reliable data pipelines.
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Advanced JavaScript
JavaScript Prototypes, Classes & Modules
Reason through prototype lookup, class behavior, private fields, inheritance, module bindings, imports, and reusable code boundaries.
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JavaScript Practice
JavaScript Testing, Debugging & Error Handling
Test assertions, async tests, mocks, stack traces, error design, debugging tools, and strategies for trustworthy JavaScript.
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Advanced JavaScript
JavaScript Performance, Memory & the Browser
Reason about measurement, rendering work, event handlers, memory retention, workers, data structures, and scalable frontend performance.
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Google Apps Script
Apps Script for Google Sheets Automation
Work through challenging questions about ranges, values, batching, formulas, filters, and reliable spreadsheet automation.
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Google Apps Script
Apps Script Triggers, APIs & Reliable Automation
Test trigger identities, event objects, locks, caching, external requests, advanced services, and production automation design.
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CSS
CSS Layout: Grid, Flexbox & Sizing
Reason through intrinsic sizing, Grid tracks, Flexbox alignment, overflow, containing blocks, and robust layout choices.
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CSS
CSS Cascade, Specificity & Maintainable Styles
Master cascade layers, specificity, inheritance, custom properties, selectors, and architecture decisions that keep CSS predictable.
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CSS
Responsive, Accessible & Modern CSS
Test container queries, logical properties, media preferences, fluid sizing, focus styles, and resilient responsive design.
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CSS
CSS Custom Properties & Theming
Build reusable themes and reason about variable scope, fallbacks, and computed values.
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JavaScript
JavaScript: Immutable State Updates
Practice copying arrays and objects without accidentally changing earlier state.
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HTML
HTML: Accessible Data Tables
Choose table structures that communicate headers, groups, and data relationships.
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JavaScript
Browser Web Workers & Messaging
Move expensive calculations off the UI thread and manage messages, results, and worker lifecycles.
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Google Apps Script
Apps Script: Locks & Shared State
Prevent overlapping executions from corrupting shared counters and workflow state.
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HTML
HTML: Native UI Patterns & Interactions
Reason through disclosure panels, dialogs, form controls, labels, and native browser behavior.
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CSS
CSS: Sizing, Overflow & Layout Debugging
Diagnose overflowing layouts, flex and grid sizing, intrinsic dimensions, and responsive content.
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Browser JavaScript
JavaScript: Component Events & DOM Updates
Read and debug event delegation, listener lifecycles, live properties, and safe DOM rendering.
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Browser JavaScript
JavaScript: Async UI States & Race Conditions
Handle overlapping searches, cancellation, stale responses, failed requests, and loading states.
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Browser JavaScript
JavaScript: URL State & Browser Navigation
Build predictable filters and navigation with query parameters, history, validation, and storage boundaries.
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JavaScript Practice
Frontend Testing: Behavior, Boundaries & Regressions
Choose meaningful frontend tests for interactions, async states, responsive layouts, and browser storage.
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Google Apps Script
Apps Script: Range & Array Code Challenges
Trace spreadsheet coordinates, array transformations, write dimensions, and formula-safe output.
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Google Apps Script
Apps Script: Trigger Events & Guard Clauses
Reason about event objects, pasted ranges, sheet guards, and controlled trigger behavior.
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Google Apps Script
Apps Script: Sidebar Client–Server Challenges
Debug HTML-service callbacks, serialization, response ordering, and server-side validation.
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Google Apps Script
Apps Script: Resumable Batch Jobs & Checkpoints
Plan resumable processing with durable cursors, locking, retry policies, and safe output ownership.
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Vibe Coding
Vibe Coding: Frontend Prototypes That Work
Turn AI-assisted interface ideas into testable prototypes with clear behavior, states, and constraints.
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Vibe Coding
Vibe Coding: Safe Changes to Existing Projects
Reason through targeted modifications, existing contracts, dependency choices, and reviewable patches.
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Vibe Coding
Vibe Coding: Evidence-Led Debugging
Use reproduction steps, competing hypotheses, minimal changes, and verification in AI-assisted debugging.
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Vibe Learning
Vibe Learning: Retrieval & Misconception Checks
Choose learning activities that reveal understanding, expose errors, and use AI feedback thoughtfully.
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Vibe Learning
Vibe Learning: Practice Plans & Progress Evidence
Build realistic practice plans, choose useful feedback, and measure learning through independent performance.
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JavaScript
JavaScript Closures & Scope
Reason through lexical scope, closures, shadowing, and function factories.
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JavaScript
JavaScript Maps, Sets & Iteration
Practice keyed collections, identity, iterables, and generator behavior.
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JavaScript
JavaScript Strings & Regular Expressions
Work through string boundaries, Unicode, replacements, and pattern matching.
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JavaScript
JavaScript Numbers, Dates & Formatting
Test numeric conversion, precision, timestamps, and locale-aware output.
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JavaScript
JavaScript Fetch & Browser Data
Practice request handling, cancellation, JSON, URLs, and browser storage.
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Google Apps Script
Apps Script Web Apps & HTML Interfaces
Connect HTML interfaces to server functions and reason about deployment access.
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Google Apps Script
Apps Script API Requests & JSON
Build dependable external API requests with explicit payloads and response handling.
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Google Apps Script
Apps Script Drive & Docs Workflows
Practice file identity, template copies, document tabs, and safe content changes.
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Google Apps Script
Apps Script Forms & Calendar Automation
Map form responses to reliable scheduling and notification workflows.
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Google Apps Script
Apps Script State & Reliable Automation
Handle persistent settings, caches, locks, checkpoints, and partial failures.
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HTML
Semantic HTML, Forms & Document Structure
Test landmark structure, forms, tables, metadata, responsive images, and the semantics that make HTML resilient.
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Accessibility
Web Accessibility & Inclusive Interfaces
Challenge your knowledge of WCAG principles, keyboard interaction, ARIA, focus, contrast, announcements, and accessible components.
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Web Development
HTTP, REST APIs & Web Communication
Reason through methods, status codes, caching, headers, authentication, idempotency, CORS, and API design.
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Security
Web Security Fundamentals for Developers
Test XSS, CSRF, authentication, authorization, cookies, password storage, headers, validation, and secure design decisions.
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Developer Workflow
Git Branching, History & Collaboration
Challenge your Git knowledge with commits, branches, merges, rebases, recovery, remotes, conflicts, and collaborative workflows.
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Databases
SQL & Relational Database Fundamentals
Test joins, keys, normalization, indexes, transactions, aggregation, NULL behavior, and safe query design.
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PHP
Modern PHP Web Development
Challenge your PHP knowledge with types, arrays, requests, sessions, PDO, namespaces, errors, security, and web application structure.
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Frontend Frameworks
React Components, State & Effects
Test component rendering, props, state, keys, effects, context, controlled inputs, and practical React design decisions.
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Performance
Web Performance & Core Web Vitals
Reason through loading, rendering, images, JavaScript, caching, metrics, fonts, and evidence-based performance improvements.
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Web Design
UX, Interface Design & Design Systems
Test usability, hierarchy, feedback, forms, navigation, research, tokens, components, and coherent interface systems.
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JavaScript
JavaScript: Promise Coordination & Partial Failure
Choose the right Promise combinator, preserve result order, and reason about partial failure and cancellation.
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JavaScript
JavaScript Intl: Localized Interface Decisions
Format numbers, dates, lists, and comparisons deliberately while keeping presentation separate from stored data.
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CSS
CSS: Logical Layout & Writing Modes
Adapt spacing, sizing, and alignment to left-to-right, right-to-left, and vertical content.
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HTML
HTML Media: Playback & Responsive Sources
Choose responsive images, text tracks, playback controls, and reliable media behavior.
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Google Apps Script
Apps Script: Properties & Configuration
Choose property scopes, serialize settings, handle missing values, and update configuration deliberately.
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Web Development
Web Forms: Validation & User Feedback
Build reliable form experiences with clear validation, recoverable errors, and accessible feedback.
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Web Development
Web Debugging & Release Checks
Diagnose broken pages, isolate failures, and verify a change before release.
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Google Apps Script
Apps Script Data Cleaning Pipelines
Design spreadsheet cleanup that preserves identifiers, validates rows, and produces reviewable output.
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Google Apps Script
Apps Script Debugging & Operations
Troubleshoot event handlers, configuration, permissions, and failed automation runs.
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Google Workspace
Google Workspace Collaboration & Sharing
Choose sensible access, review, and handover practices for collaborative files.
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Google Workspace
Google Sheets Data & Reporting Workflows
Keep collaborative spreadsheets consistent, interpretable, and ready for trustworthy reporting.
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Vibe Coding
Vibe Coding: Briefs, Prompts & Iteration
Turn an idea into a clear AI-assisted build with useful context, constraints, and acceptance criteria.
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Vibe Coding
Vibe Coding: Review, Testing & Reliability
Evaluate generated code, catch hidden failures, and keep AI-assisted changes reviewable.
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Vibe Learning
Vibe Learning: Active Practice with AI
Use AI as a practice partner through prediction, explanation, feedback, and independent attempts.
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Vibe Learning
Vibe Learning: Projects, Transfer & Reflection
Turn guided lessons into independent skills through small projects, varied problems, and honest assessment.
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