DOM

Question 1

Why do we log things to the console?

Answer 1

To verify the value, debug, and visualize input and outputs.

Question 2

What is a “model”?

Answer 2

general representation, copy

Question 3

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

Answer 3

HTML document

Question 4

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

Answer 4

JavaScript objects: a data type that can hold values

Question 5

What is a DOM Tree?

Answer 5

series of objects that make up the HTML document

Question 6

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

Answer 6

.querySelector(), getElementbyId()

Question 7

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

Answer 7

.queryselectorAll()

Question 8

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

Answer 8

it’s faster and for organizational purposes

Question 9

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

Answer 9

console.dir()

Question 10

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

Answer 10

so that it loads till the very end

Question 11

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

Answer 11

CSS selector and return the first element that matches the pattern

Question 12

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

Answer 12

returns a NodeList

Question 13

Why do we log things to the console?

Answer 13

debugging

Question 14

What is the purpose of events and event handling?

Answer 14

respond to user events

Question 15

Are all possible parameters required to use a JavaScript method or function?

Answer 15

No,

Question 16

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

Answer 16

addEventListener()

Question 17

What is a callback function?

Answer 17

function definition that is passed on as a value

Question 18

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

Answer 18

the event object

Question 19

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

Answer 19

The place where the event began

Question 20

What is the difference between these two snippets of code?

element. addEventListener(‘click’, handleClick)
element. addEventListener(‘click’, handleClick())

Answer 20

one is a callback function and another is a function with no parameter

Question 21

Does the document.createElement() method insert a new element into the page?

Answer 21

no it creates a new element

Question 22

How do you add an element as a child to another element?

Answer 22

appendChild

Question 23

What do you pass as the arguments to the element.setAttribute() method?

Answer 23

name of the attribute and the value of the attribute

Question 24

What steps do you need to take in order to insert a new element into the page?

Answer 24

get the thing we want to add to and then do create Element

Question 25

What is the textContent property of an element object for?

Answer 25

to change the text content pr retrieve the text conetent

Question 26

Name two ways to set the class attribute of a DOM element.

Answer 26

setAttrribute , className

Question 27

What are two advantages of defining a function to do create something (like the work of creating a DOM tree)?

Answer 27

reusablity, and control