reading-notes

Notes 2

What does .map() return?

• a map object

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

• map() Each list item needs a unique __.
• Values

What is the purpose of a key?

• they indicate if something has been changed or edited in the code

What is the spread operator?

• it allows you to expand objects or strings into elements

List 4 things that the spread operator can do.

• Copying an array
• Using Math functions
• Adding to state in React
• Converting NodeList to an array

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

• Math.min and math.max both return numbers within a range

Give an example of using the spread operator to add a new item to an array. (example added from https://medium.com/coding-at-dawn/how-to-use-the-spread-operator-in-javascript-b9e4a8b06fab)

• const fewFruit = [‘🍏’,’🍊’,’🍌’] const fewMoreFruit = [‘🍉’, ‘🍍’, …fewFruit] console.log(fewMoreFruit) // Array(5) [ “🍉”, “🍍”, “🍏”, “🍊”, “🍌” ]

Give an example of using the spread operator to combine two objects into one. (example added from https://medium.com/coding-at-dawn/how-to-use-the-spread-operator-in-javascript-b9e4a8b06fab)

• const objectOne = {hello: “🤪”} const objectTwo = {world: “🐻”} const objectThree = {…objectOne, …objectTwo, laugh: “😂”} console.log(objectThree) // Object { hello: “🤪”, world: “🐻”, laugh: “😂” } const objectFour = {…objectOne, …objectTwo, laugh: () => {console.log(“😂”.repeat(5))}} objectFour.laugh() // 😂😂😂😂😂

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

• you must create a function in the state you would like it operate in

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

• they pull individual sections of arrays to list specific parts

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

• with the arrow function

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

• via props

BACK TO HOME