[All skill tests](https://jobicy.com/tests.md) Skill assessment # Vue.js Composition API Composables and Dependency Injection Skills Test Evaluate how well you design, consume, and test reusable Vue Composition API logic. The test focuses on composable state, lifecycle handling, dependency injection, and safe API design. [Start the test](#test-start) Share Assessment setup Ready ## Choose the level that matches your current experience. * 01 Basic Available * 02 Intermediate Available * 03 Advanced Available Instant result Review your score after submission 20–30 Questions per assessment 15–45 min Estimated completion time 3 levels Choose your difficulty Vue.js [View category](https://jobicy.com/test-category/vue-js-basics.md) Start assessment ## Choose your level and begin. Answer without outside help so the result reflects your current knowledge. You will see your score after completing the selected assessment. Composable functions help Vue applications organize shared behavior without coupling it to component templates or global state. Effective use of refs, reactive values, lifecycle hooks, provide, and inject makes features easier to reuse, maintain, and test across a codebase. Basic Intermediate Advanced This is a demo version of the test. You may attempt up to 3 questions. To take the full test and save your results, please [log in](https://jobicy.com/dashboard-page.md) or [create an account](https://jobicy.com/dashboard-page#tab2.md). This is a demo version of the test. You may attempt up to 3 questions. To take the full test and save your results, please [log in](https://jobicy.com/dashboard-page.md) or [create an account](https://jobicy.com/dashboard-page#tab2.md). This is a demo version of the test. You may attempt up to 3 questions. To take the full test and save your results, please [log in](https://jobicy.com/dashboard-page.md) or [create an account](https://jobicy.com/dashboard-page#tab2.md). Test details ## Know what to expect. Review the instructions, covered skills, example question themes, and intended audience before beginning. 01 ### Instructions and covered skills Read each prompt carefully before selecting a response. Focus on the behavior Vue provides rather than assumptions from other frameworks. Review code snippets for ref unwrapping, lifecycle context, and shared-state implications. Choose the response that best fits the stated requirement. Keep your work independent and avoid external references. Turn off notifications and stay focused until you have reviewed every response. ### Key Areas This test examines the design and use of Vue Composition API composables. Candidates work with ref, reactive, computed, readonly, and toRefs to create APIs that preserve Vue reactivity while remaining clear to component authors. It also covers the difference between state created during each composable call and state intentionally created at module scope for sharing across component instances. Questions address lifecycle-aware logic, including registering cleanup through Vue lifecycle hooks and ensuring browser listeners, timers, subscriptions, and observers are released when a component is removed. Candidates should recognize that lifecycle hooks require an active component instance and should know when a composable is appropriate for encapsulating side effects. The assessment also covers dependency injection with provide and inject. This includes using injection keys, configuring fallback values, supplying mutable or readonly dependencies, and enabling replacement dependencies for tests or feature-specific component trees. Attention is given to dependency ownership so that consumers can use an injected service without unexpectedly controlling its internal state. ### Recommended Preparation Review Vue's Composition API documentation and build small composables for a timer, network-status monitor, or data-fetching workflow. Practice returning refs, methods, and readonly state with intentional public interfaces. Compare local state created inside a composable with shared state declared outside it, and identify the consequences for multiple component instances and server-rendered applications. Practice providing a service from an ancestor component and injecting it in descendants with a symbol key. Try supplying a fallback implementation and replacing a provided service in a test harness. Finally, inspect composables for cleanup responsibilities, caller-owned inputs, and places where destructuring could disconnect a reactive property from Vue's tracking system. 02 ### Examples of questions 1. What makes a function a Vue composable? 2. When should a composable return a ref instead of a plain value? 3. How can a component replace an injected dependency? 4. What happens when a composable creates module-scoped reactive state? 5. Where should an onUnmounted cleanup callback be registered? 6. Why might toRefs be used when returning reactive object properties? 7. How can an injection key reduce dependency-name collisions? 8. What value does inject return when no provider exists and no fallback is supplied? 9. How can a composable avoid mutating a caller-owned ref? 10. Which API exposes a readonly view of mutable composable state? 03 ### Who this test is best for Vue.js developers who build reusable application features, shared services, and component infrastructure with the Composition API. Related assessments ## Continue with a similar skill test. Explore assessments from the same professional area to compare adjacent skills and build a broader picture of your knowledge. 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