Passing Functions as Props

Reading

What does .map() return?

An array.

 

• If I want to loop through an array and display each value in JSX, how do I do that in React?

Using .map(), we make every value in the array we are mapping go through html-like code we want it in.

 

• Each list item needs a unique __.

Key.

 

• What is the purpose of a key?

Keys help React identify which items have changed, are added, or are removed.

 

• What is the spread operator?

he spread syntax “spreads” the array into separate arguments.

 

• List 4 things that the spread operator can do.

  • Copying an array
  • Concatenating or combining arrays
  • Using Math functions
  • Using an array as arguments

 

• Give an example of using the spread operator to combine two arrays.

const hello = ['hello']
const world = ['world']

const helloWorld = [...hello,...world]
console.log(...helloWorld) // hello world

 

• Give an example of using the spread operator to add a new item to an array.

const fruit1  = ['apple', 'pineapple', 'banana']
const fruit2 = ['orange']

const fruits = [...fruit1,...fruit2]
console.log(...fruits) // apple pineapple banana orange

 

• Give an example of using the spread operator to combine two objects into one.

const hello = {hello: “hayoo”} const world = {world: “globe”}

const helloWorld = {…hello,…world} console.log(helloWorld) // Object { hello: “hayoo”, world: “globe” }

Videos

• In the video, what is the first step that the developer does to pass functions between components?

make a constructor.

 

• In your own words, what does the increment function do?

Increase the number besides the names the instructor used.

 

• How can you pass a method from a parent component into a child component?

By passing it as an attribute through the html-like code (example: increment={this.increment}).

 

• How does the child component invoke a method that was passed to it from a parent component?

You can call it through this.props.increment().

301	Home
read01	Introduction to React and Components
read02	State and Props
read03	Passing Functions as Props
read04	React and Forms
read05	Putting it all together
read06	NODE.JS
read07	REST
read08	APIs
read09	FUNCTIONAL PROGRAMMING
read10	In memory storage
read11	Authentication
read12	Mongo and Mongoose
read13	CRUD
read14	Project Ideas
read15	Project Kickoff