Online React JS MCQ Test

Questions

1. We can go for __________ when there is possibility that our user could change the data.
2. JSX is typesafe.
3. React merges the object you provide into the current state using __________.
4. Arbitrary inputs of components are called __________.
5. _________ can be done while more than one element needs to be returned from a component.
6. Which of the following needs to be updated to achieve dynamic UI updates?
7. Lifecycle methods are mainly used ___________.
8. State can be initialized when code is loaded or state can be set on event changes.
9. ref is used to refer a element / component returned by _______________.
10. In JSX most of the errors can be caught during _________.
11. Components cannot refer to other components in their output.
12. If our elements are dynamic, react can keep track of the changes using keys.
13. Function that does not change its results for the same set of inputs are called __________.
14. What is the smallest building block of ReactJS?
15. An altered component may be uniquely identified with the help of ref
16. React considers everything as _______.
17. React keeps track of what items have changed, been added, or been removed from a list using ________.
18. React is mainly for building _____________.
19. React supports all the syntax of _________________.
20. In React state can be accessed using ________.
21. How can we prevent default behavior in React?
22. Invoked once, only on the client, after rendering occurs.
23. What are the limitations of ReactJS?
24. How can you access the state of a component from inside of a member function?
25. Props are __________ into other components
26. Which of the following API is a MUST for every ReactJS component?
27. At the highest level, React components have lifecycle events that fall into
28. What are the advantages of React JS?
29. What does the “webpack” command do?
30. What is a react.js in MVC?
31. props in react can________
32. State in react is________
33. Number of elements, a valid react component can return
34. Consider following example. What will be the output var Helloword=(props)=> { return (
    hello world 1
    Hello world 2
    ); } ReactDOM.render(,mountNode)
35. React is _______
36. ReactJS uses _____ to increase performance
37. ReactJS covers _________
38. Which method in a React Component should you override to stop the component from updating?
39. What's used to pass data to a component from outside?
40. Which method in a React Component is called after the component is rendered for the first time?
41. What happens when the following render() method executes? render(){ let langs = ["Ruby","ES6","Scala"] return (
    {langs.map(it =>

    {it}

    )}
    ) }
42. How does React handle Web Accessibility Initiative - Accessible Rich Internet Applications (WAI-ARIA) standard?
43. What is the command to install react router?
44. Which one is used to set the default component in react?
45. Which one is used to add a component in router?
46. Flux is a programming concept, where the data is _____
47. Dispatcher is a central hub of the app. All the data is dispatched and sent to the stores.
48. Actions are sent to the dispatcher to trigger the data flow.
49. Store is the place where the application state and logic are held. Every store is maintaining a particular state and it will update when needed.
50. The view will receive data from the store and re-render the app.
51. Higher order components are ______ used for adding additional functionalities to the existing component.
52. Higher order components are ______.
53. HOC Stands for _________.