DOM(Document Object Model)

Question 1

Why do we log things to the console?

Answer 1

SO we can see what’s going on. Better than guessing.

Question 2

What is a “model”?

Answer 2

Representation of something else.

Question 3

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

Answer 3

For this one HTML, API

Question 4

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

Answer 4

Each node is an object

attribute nodes or text nodes

Question 5

What is a DOM Tree?

Answer 5

It can be thought of as a tree with a single parent stem that branches out into several child branches.

Question 6

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

Answer 6

document. getElementById()

document. querySelector()

Question 7

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

Answer 7

document.queryselectorAll()

Question 8

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

Answer 8

If we need to work with an element more than once.

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 script tag need to be placed at the bottom of the HTML content instead of at the top?

Answer 10

The browser needs to parse all of the elements in the HTML page before the JavaScript code can access them.

Question 11

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

Answer 11

takes css selector as string?

returns the first element that matches a css selector.

Question 12

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

Answer 12

NodeList representing a list of the document’s elements that match the specified group of selectors.

Question 13

Why do we log things to the console?

Answer 13

To check if it’s working.

Question 14

What is the purpose of events and event handling?

Answer 14

to callback 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

A function passed into another function as an argument

Question 18

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

Answer 18

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?

Question 20

What is the difference between these two snippets of code?

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

Answer 20

with the handleclick(), it can’t do anything cuz it’s not calling function

Question 21

What is the className property of element objects?

Answer 21

set or return the value of an element’s class attribute

Question 22

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

Answer 22

document.queryseletor(css selector).className = string of the class name

Question 23

What is the textContent property of element objects?

Answer 23

sets or returns the textual content of the specified node, and all its descendants.

Question 24

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

Answer 24

elemet.textContent = ‘’

Question 25

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

Answer 25

Not always

Question 26

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

Answer 26

Would say harder.

Question 27

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

Answer 27

Numbers aren't DOM element, so we need to use a variable to assign a numeric values.

Question 28

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

Answer 28

No it doesn't

Question 29

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

Answer 29

appendchild

Question 30

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

Answer 30

pass the values of the attributes and the values as string

Question 31

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

Question 32

What is the textContent property of an element object for?

Answer 32

generate texts to the nodes.,

Question 33

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

Answer 33

setAttribute, classname

Question 34

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

Answer 34

To repeat | We can change it any time we want.

Question 35

What is the event.target?

Answer 35

reference to the object onto which the event was dispatched. point of interaction

Question 36

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

Answer 36

The event bubbling: The event starts at the most specific node and flows outwards to the least specific one., it's the default

Question 37

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

Answer 37

tagName

Question 38

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

Answer 38

takes css selector, and it returns the closest parent element. also could return iself

Question 39

How can you remove an element from the DOM?

Answer 39

.remove() method

Question 40

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 40

Use bubbling