REACT Practice Test

Question 1

Which of the following React functions will update the data of a component while remaining within the componentWillMount?

Accepted Answer

setState()

Answer

The `setState()` function is the primary way to update a component's state in React, triggering a re-render. While `componentWillMount` is a legacy lifecycle method called before the component mounts, calling `setState()` within it allows you to update the component's state before the initial render, ensuring the component mounts with the desired data. However, for new code, `constructor` for initial state or `componentDidMount` for data fetching is generally preferred.

Question 2

What does React not include?

Accepted Answer

All of the above

Answer

React is a library primarily focused on building user interfaces, specifically the 'V' in MVC. It intentionally does not include features like a built-in data layer (leaving that to state management libraries like Redux), its own AJAX capabilities (relying on standard JavaScript APIs like `fetch` or `axios`), or a comprehensive event system beyond synthetic DOM events. This modularity allows developers to choose their preferred tools for these concerns.

Question 3

Which step should be completed first when configuring Gulp on a developer machine?

Accepted Answer

Define a gulpfile.js

Answer

When setting up Gulp, the first essential step after installing Gulp globally and locally is to create a `gulpfile.js` file in your project's root directory. This file is where you define all your Gulp tasks, specifying what operations Gulp should perform, such as compiling SASS, minifying JavaScript, or running a local server. Without this file, Gulp has no instructions to execute.

Question 4

Which JavaScript API may be used to delete an item from a Flux store's private storage?

Accepted Answer

Lodash

Answer

Lodash is a popular JavaScript utility library that provides a wide range of helper functions for common programming tasks, including manipulating arrays and objects. While Flux stores manage their own state, Lodash functions like `_.omit` or `_.without` can be used within a store's logic to immutably remove items from its private data structures, making it a useful tool for state management operations within the store.

Question 5

For type verification in React components, what property name is used?

Accepted Answer

propTypes

Answer

In React, `propTypes` is a special static property used within a component definition to specify the expected data types for the props it receives. This mechanism helps with type checking during development, providing warnings in the console if props don't match the defined types. It's a valuable tool for ensuring component reliability, maintainability, and clear communication of component interfaces.

React Practice Test

React Practice Test

REACT Practice Test