Main

Question 1

RN has how many main threads?

Answer 1

Two?
JavaScript business logic
UI thread on native device
bridge (is this a thread)?

REVISIT

Question 2

List the main three RN threads.

Answer 2

UI thread
JavaScript thread (the business logic)
the bridge (communication between UI & JS threads)

Question 3

RN is ____ - threaded.

Answer 3

single

Question 4

RN suffers in performance in apps that need to run ____ features ____ .

Answer 4

multiple

simultaneously

Question 5

In RN apps, performance issues could arise since the single-threaded nature of it dictates that components have to ____ when another component is being rendered.

Answer 5

wait

Question 6

The InteractionManger is used to prevent what from happening?

Answer 6

The UI thread dropping frames

Question 7

The FlatList api ____ list view performance.

Answer 7

optimizes

Question 8

React Native alternatives like Cordova run a single-page app inside of a ____ , whereas React Native uses ____ .

Answer 8

WebView (the mobile browser engine)

native UI modules

Question 9

Three major differences from RN vs React for web:

Answer 9

RN doesn’t have HTML,
doesn’t have CSS,
routing is handled differently
JS runs on JavaScriptCore, instead of V8 engine

Question 10

True or False: RN uses babel

Answer 10

true

Question 11

RN uses ____ as its JavaScript enginel

Answer 11

JavaScriptCore

Question 12

Name the three most common RN UI modules.

Answer 12

Image, Text, View

Question 13

What is one method to use from the FlatList api that lets you optimize list performance if you know list item height ahead of time?

Answer 13

getItemLayout()

Question 14

What is the RN equivalent of the React for web key prop that’s used for list items?

Answer 14

keyExtractor

Question 15

What UI module do you use to get the height and width of the app window?

Answer 15

Dimensions

Question 16

What UI module do you use to link to external sources from within an app?

Answer 16

Linking

Question 17

If you wanted to add an infinite scrolling ActivityIndicator to the bottom of a FlatList, what component prop would you put that inside of?

Answer 17

ListFooterComponent

Question 18

Where do performance bottlenecks occur in React Native apps?

Answer 18

the bridge between the JS engine and the native UI thread

Question 19

The bridge ____ data before sending it to the native UI thread.

Answer 19

serializes

Question 20

FlatList optimizes list performance by only rendering ____ , and un-mounting ____ .

Answer 20

rows that are visible on the screen

rows that have been scrolled past

Question 21

Metro is the ____ ____ for React Native.

Answer 21

JavaScript bundler

Question 22

There are two main ways to scaffold a RN project. What are these?

Answer 22

Expo cli and React Native cli

Question 23

Expo makes it very easy to publish ____ ____ ____ updates to your app.

Answer 23

Over The Air (OTA)

Question 24

One limitation of an Expo build (a non-bare build) is that you don’t have access to ____ ____.

Answer 24

native code

Question 25

One Expo limitation regarding API’s is that ________.

Answer 25

not all iOS and Android API’s are available

Question 26

In an Expo “bare” build, you have access to the ____ iOS and Android code.

Answer 26

native

Question 27

One downside of using Expo is that your build size may be larger than necessary due to ________.

Answer 27

All APIs being included whether they are used or not

Question 28

Expo provides two workflow options for project builds: ____ and ____.

Answer 28

managed

bare

Question 29

One downside to using Expo is that ____ ____ ____ updates are limited by ____ restrictions.

Answer 29

Over The Air

size

Question 30

The four main tools/libraries that you need to build a RN project without using Expo is:

Answer 30

Xcode, Node, Watchman, React Native CLI

Question 31

Watchman is a tool built by Facebook that does what?

Answer 31

Watches for file changes

Question 32

Cocoapods ____ ____ dependencies for Xcode projects.

Answer 32

manages libraries