Basic JavaScript

Question 1

Declare variables of type number, string, boolean, and undefined. (Not constants)

Answer 1

let someNum = 42;

let username = “playerOne”;

let isThisBool = true;

let iDunno = undefined;

Question 2

Declare a constant of type string for username.

Answer 2

const username = “playerOne”;

Question 3

Declare two numbers variables on the same line.

Answer 3

let numOne = 41, numTwo = 42;

Question 4

A single line comment

Answer 4

// Single line of comment code

Question 5

Multiple line comment

Answer 5

/* Multi
Line
Comment */

Question 6

Increment and decrement a number variable by one.

Answer 6

someNumber++;
someNumber–;

Question 7

Print a string to the browser console.

Answer 7

console.log(“Some String”);

Question 8

Access a specific character from a string.

Answer 8

someString = “All these words:;

someCharacter = someString[0]; //First character

Question 9

Basic conditional statement: if num is greater than 0, print a message to the console, else print another message.

Answer 9

if (num > 0) {
console.log(“Greater than zero”);
} else if (num =< 0) {
console.log(“NOT Greater than zero”);
}

Question 10

Check if numOne and numTwo are STRICTLY equal.

Answer 10

if (numOne === numTwo){
console.log(“Yeah, it is”);
}

Question 11

JavaScript syntax for AND, OR, Not Equal

Answer 11

&& (true && false)
|| (true || false)
! true

Question 12

Switch (case) statement to set the “creator” variable based on the value of the “os” variable.

Answer 12

let creator;
switch (os) {
case “linux”:
creator = “Linus Torvalds”;
break;
case “windows”:
creator = “Bill Gates”;
break;
case “mac”:
creator = “Steve”;
break;
default:
creator = “Unknown”;
break;
}

Question 13

Using a Ternary operator, set a variable’s value based on a condition.

Answer 13

const price = isMember ? “$2.00” : “$10.00”;

*After the question mark it the True value followed by the False value.

Question 14

Using Nullish Coalescence, check for a name variable to be null, set a value accordingly.

Answer 14

let myName = null;
someName = myName ?? “Anonymous”;

Question 15

Create a basic function that multiplies two numbers.

Answer 15

function multiplyTwoNums(numOne, numTwo){
let multi = numOne * numTwo;
return multi;
}

Question 16

Anonymous function

Answer 16

// using an anonymous function
conversions(
function (a) {
return a + a;
},
1,
2,
3,
);
// 2 4 6

Question 17

Define an immediately invoked function expression (IIFE) that declares a variable of result equal to the sum of a + b.

Answer 17

const result = (function (a, b) { return a + b; })(1, 2);

console.log(result); // 3