What is this piece of Objective-C code doing?

If I have a pure function with a very heavy computation cost that takes arguments a & b and returns a response - if it is called many times, what is a way we can optimize this function's performance?

For Interviewer - Were they able to explain the technical concepts with clarity?

There are different React Patterns. Can you explain what is a HOC, Render Prop and a Custom Hook? (2 out of 3 correct is okay)

If I needed a analytics function to be called when a React function component unmounts where is the right place to put that in a Function component?

While trying to build our React Native iOS project we got the following error, what do you think the problem is? 

How do you promisify this delay function? Right now it logs start, finish, timeout, we want it to log start, timeout, finish.

Take a look at this simple React form snippet, can you add a controlled password input and only allow for the user to click the submit button if the password is at least 8 characters long?

What are the different ways improve performance of a React application?

Classes - What do you need to do to define name and age when instantiating the Person class?

What are the different ways to implement platform specific code in React Native?

What are mocks? Follow up - When doing end-to-end and unit testing which one should you not use any mocks?

What is the difference between imperative and declarative programming paradigms? Follow up with: Where does functional programming and procedural programming fall in-betweent the two?

Our client complained that our React Native app has a very slow initial load, what would you consider that could be a problem?

Which are the main list components available in React Native and how do you pick which one to use? What are the differences between them?

In a form, we want to implement a user flow where on every TextInput edit complete we automatically focus the keyboard on the next input, how can that be done in React Native?

What is a use case for class components today?

Can you write a native module that calls into JavaScript and receives the response synchronously? Explain

Compared to the Animated API, why does the Reanimated library exist, what is it trying to solve?

Given this array of users, can you implement the return of getActiveUsersWithCat to return only active users with cats?

Can you explain the createNewUser function, what kind of argument it takes? What are these different syntaxes doing like the equal signs and tripple dot?

Functions - Why was the arrow function introduced into JavaScript?

Spread Syntax & Shallow Copy - Why does log 1 show the new email and not the old email in this code example?

React Native Interview - 2021

Includes passing tests (unit, component, etc)

Self written README that explains how to install/run app

Business logic is centralized in one place (Not in a component)

API knowledge is centralized in one place (not in a component)

Correct usage of setState in Lifecycle methods

Data is not fetched from inside components

Separates components from screens/containers in source

Correct implementation of a community accepted navigation library

Final determination to move forward with candidate?

Makes use of basic React APIs like: useEffect, useState, Class component lifecycles, setState, useContext, etc.

Does not use imperative for-loop prefers Array methods

Does not duplicate data or state across the app

Handles vertical spacing for React Native

Treats API errors and displays appropriate error message

UI is sane - Big enough buttons, no unexpectedly moving UI elements during quiz switch, list items are all visible, UI is functional.

Makes use of JavaScript helper methods like Array.map, Array.filter, Array.reduce, Object.keys, etc.

Implements a custom hook or a HOC to encapsulate logic in React

Trivia App - Uses a ScrollView for the 10 item results list.

Code Challenge - Includes instructions on how to run the project in a development environment

Trivia Challenge - Normalizes the data received from the API

Uses keys for the React list item components

Breaks up the UI with components, has at least one reusable component

Use naming conventions for variables,constants, functions, classes

Trivia Challenge - Implements the trivia quiz.

Trivia Challenge - Handles navigation to the different parts of the app.

Does not mutate an object function argument

Always awaits promises or resolve them. Does not use callbacks

Trivia Challenge - Isolates network request in a service module or function

Agustin Vazquez

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