DOM

Question 1

Why do we log things to the console?

Answer 1

To check that the correct output is being made, debugging, knowing what you’re working with

Question 2

What is a “model”?

Answer 2

Represents the structure of the document. Recreation, representation

Question 3

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

Answer 3

The HTML document

Question 4

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

Answer 4

the data type object in javascript

Question 5

What is the DOM?

Answer 5

Dom is a javascript object that has been constructed to recreate the content of the HTML document

Question 6

What is a DOM Tree?

Answer 6

An element and all of its configurations and content represented as an object in the dom.

Question 7

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

Answer 7

getElementById() and document.querySelector()

Question 8

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

Answer 8

document.querySelectorAll()

Question 9

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

Answer 9

If your script needs to use the same element more than once

Question 10

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

Answer 10

console.dir()

Question 11

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

Answer 11

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

Question 12

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

Answer 12

string of Css selector and returns only the first of the matching elements

Question 13

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

Answer 13

Css selector and returns Nodelist(collection of nodes)/ all of those elements that match

Question 14

Why do we log things to the console?

Answer 14

To see the result of our output, to know what we are working with

Question 15

What is the purpose of events and event handling?

Answer 15

Event - something that occurred. Listener is waiting and calls event handler. The purpose of events is to react to them through event handling, the next step to do

Question 16

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

Answer 16

no

Question 17

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

Answer 17

addEventListener(‘name of event as a string’, function you want to run)

Question 18

What is a callback function?

Answer 18

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 19

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

Answer 19

An object that has properties to describe the event that occurred

Question 20

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

Answer 20

Element that triggered the event, where did it begin.
Console log and mdn

Question 21

What is the difference between these two snippets of code?

Answer 21

element.addEventListener(‘click’, handleClick) - passes the function as a value, a call back, when event occurs
element.addEventListener(‘click’, handleClick()) - runs the function right now and replaces it with return value of undefined. Breaks and will not add event listener

Question 22

What is the className property of element objects?

Answer 22

Get or set the class attribute of element

Question 23

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

Answer 23

element.className = ‘ ’;

Question 24

What is the textContent property of element objects?

Answer 24

get or set the text content of the element

Question 25

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

Answer 25

element.textContent = ‘ ‘;

Question 26

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

Answer 26

no

Question 27

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

Answer 27

complicated

Question 28

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

Answer 28

easy access for javascript instead of depending on another language to convert So we don’t have to use nodes in the dom and have easy access to the variables

Question 29

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

Answer 29

no

Question 30

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

Answer 30

parentelement.appendChild(childelement);

Question 31

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

Answer 31

element.setAttribute(‘name of value’, ‘value’)’; ex: ‘class’, ‘container’

Question 32

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

Answer 32

Create element, configuration like text content, applyc lasses, then query for parent element, append to parent.appendChild(elementhere);

Question 33

What is the textContent property of an element object for?

Answer 33

Adding text to a element or see what it is

Question 34

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

Answer 34

elementname.setAttribute(‘name of value’, ‘value’)’ or element.classname = ‘ ‘;

Question 35

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

Answer 35

Reusable for any situation using the same
no need to type everything out again

Question 36

What is the event.target?

Answer 36

Target of the event

Question 37

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

Answer 37

Event bubbling

Question 38

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

Answer 38

event.tagName

Question 39

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

Answer 39

A string of css selector and returns its closest ancestor element thats matching the css selector

Question 40

How can you remove an element from the DOM?

Answer 40

element.remove();

Question 41

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 41

Use event delegation so add an even listener on the parent element