JS

Question 1

What is the className property of element objects?

Answer 1

Property holding the class attribute of that element

Question 2

How do you update the CSS class attribute of an element using JavaScript?

Answer 2

object name.class name

Question 3

What is the textContent property of element objects?

Answer 3

The text containing the element and it’s children

Question 4

How do you update the text within an element using JavaScript?

Answer 4

objectname.text content

Question 5

Is the event parameter of an event listener callback always useful?

Answer 5

not always

Question 6

Would this assignment be simpler or more complicated if we didn’t use a variable to keep track of the number of clicks?

Answer 6

more difficult

Question 7

Why is storing information about a program in variables better than only storing it in the DOM?

Answer 7

it’s more work for the browser

Question 8

Why do we log things to the console?

Answer 8

to check for errors

Question 9

What is the purpose of events and event handling?

Answer 9

so that developers would scan response

Question 10

What do [] square brackets mean in function and method syntax documentation?

Answer 10

denotes that it’s optional can be provided or not

Question 11

What method of element objects lets you set up a function to be called when a specific type of event occurs?

Answer 11

add event listener

Question 12

What is a callback function?

Answer 12

function within a function

Question 13

What object is passed into an event listener callback when the event fires?

Answer 13

a huge object when the event is passed containing all the info

Question 14

What is the event.target? If you weren’t sure, how would you check? Where could you get more information about it?

Answer 14

element target which event originated from

Question 15

What is a “model”?

Answer 15

a represenation of something

Question 16

Which “document” is being referred to in the phrase Document Object Model?

Answer 16

html document

Question 17

What is the word “object” referring to in the phrase Document Object Model?

Answer 17

objects in js

Question 18

What is a DOM Tree?

Answer 18

map representing all elements and its children

Question 19

Give two examples of document methods that retrieve a single element from the DOM.

Answer 19

query selector to get element by id

Question 20

Give one example of a document method that retrieves multiple elements from the DOM at once.

Answer 20

query selector all

Question 21

Why might you want to assign the return value of a DOM query to a variable?

Answer 21

store the location of the element

Question 22

What console method allows you to inspect the properties of a DOM element object?

Answer 22

console.dir

Question 23

Why would a tag need to be placed at the bottom of the HTML content instead of at the top?

Answer 23

allows html elements to load first

Question 24

What does document.querySelector() take as its argument and what does it return?

Answer 24

element, class, id

Question 25

What does document.querySelectorAll() take as its argument and what does it return?

Answer 25

css selector, string, returns a node list