reading-notes

🗒️ Class 03: Passing Functions as Props

What does .map() return?

If there are no other functions or expressions called when using the map function, what returns is a new array with values mapped to the original array.
If I want to loop through an array and display each value in JSX, how do I do that in React?

If we want to loop through an array and display the value in react, we could embed it in a return in between curly brackets with an inline map() function.
Each list item needs a unique __.

Each item needs a unique key
What is the purpose of a key?

The purpose of a key is to help react identify changes to an item (add, update, remove, etc.)

What is the spread operator?

The spread operator ... is a syntax used to add items to an array, combine array, objects, and to spread an array out into funtion arguments.
List 4 things that the spread operator can do.

Add items to an array, combine arrays, combine objects, and spread an array into function arguments.

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

let array1 = [1, 2, 3];
let array2 = [3,4,5];
let combinedArray = ...[...array1,...array2];
// **OR** //
let combinedArray2 = [...array1,...array2];

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

let originalArray = [0]
let array1 = [1, 2, 3];
let addedArray = [originalArray, ...array1];

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

let object1 = {one: 1};
let object2 = {two:2};
let copiedArray = {...object1, ...object2};

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

Figure out what state we are trying ot change and Create the function whereever that is.
In your own words, what does the increment function do?

Passes in a specific person’s name, find the matching name in the array/object and update that specific one.
How can you pass a method from a parent component into a child component?

By passing it in as a props from the parent component to a child component.
How does the child component invoke a method that was passed to it from a parent component?

by using the this.props.methodName()