Class 29

Question 1

What is a program?

Answer 1

A set of instructions that you write to tell a computer what to do

Question 2

What is a programming?

Answer 2

A task of writing instructions in a language that computer can understand

Question 3

What does variables do?

Answer 3

Store information

Question 4

How to create/declare a variable?

Answer 4

Use the keyword “let”

Question 5

Conditional syntax

Answer 5

if (condition is true) {
//do this
else if (….) {
//do that
else {
// do this then
}

Question 6

Multiple conditions (and)

Answer 6

if (name === “Leon” && status === “Balling”) {
do this
}

Question 7

Multiple conditions (or)

Answer 7

if (day === “Saturday” || day === “Sunday”) {
It is the weekend
}

Question 8

What are functions?

Answer 8

Reusable sets of instructions

Question 9

Functions

Answer 9

function yell (word) {
alert(word)
}

yell(“Hello”)

Question 10

What are loops?

Answer 10

Repeat an action some number of times

Question 11

What are 3 main types of loops in js?

Answer 11

For, while and do while loops

Question 12

For loop

Answer 12

for (let i = 1; i < 5; i++) {
console.log(i)
}

Question 13

In order to create function in js, what keyword do you need?

Answer 13

function

Ex.
function toCelsius(temp) {
… }

Question 14

What are arrays?

Answer 14

A data structure to store ordered collection
Array elements are numbered starting with zero
Arrays have many methods to manage the order of elements
Arrays are populated with any type of elements (string, boolean or number)

Question 15

How to create arrays?

Answer 15

Through literal notation or a constructor

Question 16

Declaring arrays through literal notation

Answer 16

let newArr = []

Question 17

Array iteration

Answer 17

Iterate through an array passing in the value and index of each element
newArr.forEach((x,i) => console.log(x))

Question 17

Array length

Answer 17

console.log (newArr.length)

Question 18

Explain the reduce method of an array

Answer 18

Reduces an array into a single value by passing a callback function on each element of an array

Question 19

Syntax of a reduce method of an array

Answer 19

const sum = array1.reduce(
(accumulator, currentValue) => accumulator + currentValue,
initialValue,
)

Question 20

When to use array.reduce()?

Answer 20

Sum

Question 21

What does filter method of an array do?

Answer 21

The filter() method creates a new array filled with elements that pass a test provided by a function.