Variables

Question 1

What are variables?

Answer 1

They are like containers that store information in the computer’s memory. Can be primitive data types

Question 2

What can you do with variables?

Answer 2

1) Create a variable with a descriptive name
2) Store or update information stored in a variable.
3) Reference or “get” information stored in a variable

Question 3

Whats the short hand for variable in ES6?

Answer 3

var
Note: Variables cannot start with numbers
-are case sensitive
-Cannot be the same as keywords https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#Keywords

Question 4

What is the =?

Answer 4

the assignment operator used to assign a value to a variable.

Question 5

What is let?

Answer 5

signals that the variable can be reassigned a different value. Ex)
let meal = 'Enchiladas';
console.log(meal); // Output: Enchiladas
meal = 'Burrito';
console.log(meal); // Output: Burrito

Question 6

What is const?

Answer 6

Variable that is constant, cannot be changed

Question 7

What are the math assignment operators?

Answer 7

Symbols set to not mathematical operations: -=, *=, and /=
Ex)

let x = 20;
x -= 5; // Can be written as x = x - 5
console.log(x); // Output: 15

let y = 50;
y *= 2; // Can be written as y = y * 2
console.log(y); // Output: 100

let z = 8;
z /= 2; // Can be written as z = z / 2
console.log(z); // Output: 4

Question 8

What are the Increment and Decrement Operator?

Answer 8

increment operator (++) and decrement operator (–). Communicates the value of variable to increase or decrease by 1

Question 9

How would I write a variable that prints out: ‘I own a pet armadillo.’

Answer 9

let myPet = 'armadillo';
console.log ("I own a pet " + myPet + ".");

Question 10

What is string interpolation?

Answer 10

You to build a string template (Template literal) with backticks (` `) and insert a variable using ${var}
-We interpolate `I own a pet ${myPet}.` into output: 'I own a pet armadillo.'
Ex)
const myPet = 'armadillo';
console.log(`I own a pet ${myPet}.`);
// Output: I own a pet armadillo.

Question 11

How do you check for data type of a variable?

Answer 11

const unknown1 = 'foo';
console.log(typeof unknown1); // Output: string

const unknown2 = 10;
console.log(typeof unknown2); // Output: number

const unknown3 = true; 
console.log(typeof unknown3); // Output: boolean

Question 12

What do you get if variables that have not been initialized display:

Answer 12

‘undefined’