1.1 What Is JavaScript

Question 1

What Is JavaScript?

Answer 1

JavaScript (or simply JS) is the programming language of the web browser.

Question 2

What is client-side programming?

Answer 2

the code runs on the client’s computer or device

Question 3

What is server-side programming?

Answer 3

code is executed on a server and not on the user’s computer.

Question 4

What does DOM stand for?

Answer 4

Document Object Model

The DOM, which stands for Document Object Model, is a programming interface for HTML.

Question 5

What are functions?

Answer 5

functions are reusable pieces of code. Instead of writing the same code over and over again when you want to reuse it, you can put it inside a function and call the function where you need it.

Question 6

What does the: alert() function do?

Answer 6

It’s predefined to open a pop-up in your browser.

Question 7

()

Answer 7

Functions in JavaScript always have parentheses at the end, within which you can define custom parameters.

Click me!

Question 8

onclick

Answer 8

onclick is a predefined HTML attribute.

Question 9

Developer Tools Console

Answer 9

Option + Cmd + i

Question 10

What happens:

alert(‘Hello world’);

Answer 10

pop-up with the text “Hello world”.

Question 11

What happens:

console.log(‘Hello world’);

Answer 11

This function will print the given text to the console.

Question 12

How do you clear the console screen?

Answer 12

“Cmd + L” or “Ctrl + L”.

Question 13

Inline

Answer 13

“Inline JavaScript” means placing pieces of JavaSript directly into your HTML file, like this:

Click me!

Question 14

Where should the tag go?

Answer 14

at the very bottom of the page, right before the closing body tag

Question 15

Folder Structure:

Answer 15

simple-js-app:

css/
   styles.css
index.html
js/
   scripts.js

Question 16

How do you include script in your “index.html” page?

Answer 16

at the very bottom of the page, right before the closing body tag

Question 17

Comments in JS:

Answer 17

// - Single line comment

/* bla bla bla */

Question 18

Where should comments be placed?

Answer 18

before the piece of code they reference.

Question 19

What are Variables?

Answer 19

Variables are used to store—and later re-access—a piece of data, such as text or a number.

the value they store can be changed at any point in time.

var age = 29;
var name = 'Anne';

Question 20

console.log

Answer 20

Outputs to the console

Question 21

Names of Variables must:

Answer 21

It must start with a letter

It can only consist of letters, numbers, or underscores (“_”)

It can’t include any special characters, such as ü or à

Examples:

age
myAge
my_age
addressLine2

Question 22

Are Variables case sensitive?

Answer 22

Yes

Thus, myAge and myage would be two completely different variables. So would MY_AGE, and my_age.

Question 23

var josesAge = 35;
var lisasAge = josesAge;

Answer 23

you can assign one variable’s value to a second variable

Question 24

var myName = 'John Doe';
myName = 'John Doe Jr';

Answer 24

You can also assign a new value to an existing variable

when changing the value of a variable, you simply start with the variable name and don’t use var.

Question 25

document.write()

Answer 25

will write something on your document. Example: ``` var myName = 'Bob'; document.write(myName); ```

Question 26

True or False every command in JavaScript must end with a semicolon: ;

Answer 26

True

Question 27

Is this correct? Why or why not? ``` document.write(myName); var myName = 'Bob'; ```

Answer 27

code is always executed top to bottom, line by line. Above, the contents of the variable myName in document before the browser even understood what myName stands for

Question 28

var

Answer 28

Variable

Question 28

Mathematical expressions?

Answer 28

+, -, *, / ``` var simpleAddition = 2 + 2; document.write(simpleAddition); ```