React JS Interview Questions.
- We can go for keys when there is possibility that our user could change the data.
- Keys
ref
both
none of above
- JSX is typesafe.
- React merges the object you provide into the current state using __________.
- Arbitrary inputs of components are called __________.
Keys
- _________ can be done while more than one element needs to be returned from a component.
Abstraction
Packing
Insulation
- Which of the following needs to be updated to achieve dynamic UI updates?
- Lifecycle methods are mainly used ___________.
To keep track of event history
to enhance components
- freeup resources
none of the options
- State can be initialized when code is loaded or state can be set on event changes.
False
- ref is used to refer a element / component returned by _______________.
react()
- render()
reduce()
refer()
- In JSX most of the errors can be caught during _________.
Interpretation
Execution
- Components cannot refer to other components in their output.
True
- JSX is faster because it performs ____________ while compiling code to JavaScript
Modification
Compression
- If our elements are dynamic, react can keep track of the changes using keys.
- Function that does not change its results for the same set of inputs are called __________.
- Pure functions
Impure Functions
- What is the smallest building block of ReactJS?
none of the options
props
- An altered component may be uniquely identified with the help of ref.
True
- React considers everything as _______.
User interface
elements
- React keeps track of what items have changed, been added, or been removed from a list using ________.
state
props
- React is mainly for building _____________.
Database
Connectivity
- User interface
Design platform
- React supports all the syntax of _________________.
- ES6
Redux
None of options
Native Java
- In React state can be accessed using ________.
current
- How can we prevent default behavior in React?
None of the options
using revokeDefault()
- Using preventDefault()
using avoidDefault()
- Invoked once, only on the client, after rendering occurs.
componentWillUnmount
shouldComponentUpdate
componentWillMount
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