Dom

Question 1

Why do we log things to the console?

Answer 1

To debug

Question 2

What is a “model”?

Answer 2

In this case, it’s the DOM tree displayed in a pattern or representation

Question 3

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

Answer 3

HTML

Question 4

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

Answer 4

data type

Question 5

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

Answer 5

getElementbyId(‘id’) and querySelector(‘css selector’)

Question 6

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

Answer 6

querySelectorAll(‘css selector’)

Question 7

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

Answer 7

easier find and access

Question 8

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

Answer 8

console.dir()

Question 9

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

Answer 9

The browser needs to parse all of the elements of the HTML page before the Javascript code can access them. Simply because HTML needs to load before the script.

Question 10

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

Answer 10

Uses CSS selector syntax that would select one or more elements. This method returns only the first of the matching elements.

Question 11

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

Answer 11

Uses a CSS selector syntax to select one or more elements and returns all of those that match (returns a node list)

Question 12

What is a DOM Tree?

Answer 12

model for a family tree containing its attributes and values as well

Question 13

What is the purpose of events and event handling?

Answer 13

So that we get a reaction and execute it

Question 14

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

Answer 14

JavaScript function definitions do not specify data types for parameters. JavaScript functions do not perform type checking on the passed arguments. JavaScript functions do not check the number of arguments received.

Question 15

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

Answer 15

addEventListener()

Question 16

What is a callback function?

Answer 16

gets called back into calling scope

Question 17

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

Answer 17

target is where the event happens, console.log to check

Question 18

What is the className property of element objects?

Answer 18

dom method used to apply the className to a element object

Question 19

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

Answer 19

assign a new value to the property,

Question 20

what is the textContent property of element objects?

Answer 20

allows to manipulate text context, text.content property can also allow you to view the contents of the text.content property

Question 21

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

Answer 21

assigned a new value

Question 22

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

Answer 22

no

Question 23

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

Answer 23

harder, variables help organize and easier to debug/call

Question 24

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

Answer 24

easier to access or find

Question 25

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

Answer 25

no, it still needs to be added into the DOM tree

Question 26

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

Answer 26

appendChild

Question 27

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

Answer 27

name of attribute , value

Question 28

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

Answer 28

document.createElement() and appendChild()

Question 29

What is the textContent property of an element object for?

Answer 29

to add textContent

Question 30

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

Answer 30

className property, setAttribute

Question 31

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

Answer 31

ready made tool to re-use to add things in, much easier to test

Question 32

What is the event.target?

Answer 32

event where element occurs

Question 33

Why is it possible to listen for events on one element that actually happens its descendent elements?

Answer 33

bubbling

Question 34

What is DOM element property tells you what type of element it is?

Answer 34

tagName

Question 35

What does the element.closest() method take as its argument and what does it return?

Answer 35

traverses the Element and its parents (heading toward the document root) until it finds a node that matches the provided selector string. Will return itself or the matching ancestor

Question 36

How can you remove an element from the DOM?

Answer 36

.remove() method

Question 37

If you wanted to insert new clickable DOM elements into the page using Javascript, how could you avoid adding an event listener to every new element individually?

Answer 37

attach them to parent

Question 38

What is the affect of setting an element to display: none;?

Answer 38

hides element from viewport and makes it take no space

Question 39

What does the element.matches() method take as an argument and what does it return?

Answer 39

takes the string of a css selector and returns a boolean

Question 40

How can you retrieve the value of an element's attribute?

Answer 40

getAttribute()

Question 41

At what steps of the solution would it be helpful to log things to the console?

Answer 41

when you need to evaluate a value, every step is shown

Question 42

If you were to add another tab and view to your HTML, but you didn't use event delegation, how would your JS code be written instead?

Answer 42

you would have to type everything out and not be able to reuse

Question 43

If you didn't use a loop to conditionally show or hide the views in the page, how would you JS code be written instead?

Answer 43

a huge chunk of if-else statements

Question 44

What is the event.target?

Answer 44

holds the target that triggers the event