DOM

Question 1

Why do we log things to the console?

Answer 1

for debugging and an easy way to inspect your variables in the browser

Question 2

What is a “model”?

Answer 2

representation of a person or thing or of a proposed structure, typically on a smaller scale than the original.

Question 3

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

Answer 3

HTML page

Question 4

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

Answer 4

javscript objects

Question 5

What is a DOM Tree?

Answer 5

When the browser loads a web page, it creates a model of the page in memory.

Question 6

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

Answer 6

getElementByld(‘id’) , querySel ector(‘css selector’)

Question 7

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

Answer 7

getElementByClassName

Question 8

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

Answer 8

It stores the location of that elelment, properties and methods of that element work on the varaiable

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

linear, has to be at bottom so elements can load first

Question 11

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

Answer 11

css selector and returns the first matching element

Question 12

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

Answer 12

css selector and returns all matching element

Question 13

Why do we log things to the console?

Answer 13

for debugging and an easy way to inspect your variables in the browser

Question 14

What is the purpose of events and event handling?

Answer 14

make webages interactable respond to the actions of the users

Question 15

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

Answer 15

gives an option to use parameters

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(‘event’,function, flow = false)

Question 17

What is a callback function?

Answer 17

A callback function is a function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action.

Question 18

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

Answer 18

the event object with a whole lot of information about the current info

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 target property of the Event interface is a reference to the object onto which the event was dispatched. MDN

Question 20

What is the className property of element objects?

Answer 20

The className property of the Element interface gets and sets the value of the class attribute of the specified element.

Question 21

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

Answer 21

.className

Question 22

What is the textContent property of element objects?

Answer 22

The textContent property of the Node interface represents the text content of the node and its descendants.

Question 23

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

Answer 23

textContent

objectname.textContent = ‘new string’;

Question 24

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

Answer 24

more work for the browser

Question 25

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

Answer 25

creates an element that can be added to the DOM tree

Question 26

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

Answer 26

appendChild()

Question 27

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

Answer 27

Element.setAttribute(name, value);

Question 28

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

Answer 28

document.createElement , appendChild()

Question 29

What is the textContent property of an element object for?

Answer 29

property of the Node interface represents the text content of the node and its descendants.

Question 30

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

Answer 30

setattribute and className property

Question 31

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

Answer 31

reusability and makes code look cleaner/easy to read