JavaScript

Question 1

• What is a function in JavaScript?

Answer 1

a set of statements that performs a task or calculates a value

Question 2

• Describe the parts of a functiondefinition.

Answer 2

Function keyword
the first line (including the argument declarations), and the so-called body of the function

Question 3

• Describe the parts of a functioncall.

Answer 3

the name of the function being executed followed by a list of values, called arguments, which are assigned to the parameters in the function definition

Question 4

• When comparing them side-by-side, what are the differences between a functioncalland a functiondefinition?

Answer 4

The definition has a code block while the call doesn’t
Parameter are a new thing while the call is just inserting something

Function keyword

Question 5

• What is the difference between aparameterand anargument?

Answer 5

Parameter are place holder names for when something is defined

Arguments are used when it is called .

Question 6

• How do you compare two different expressions in the same condition?

Answer 6

Using one of the logical operators &&, ||

Question 7

What is the event.target?

Answer 7

It is a reference to the object onto which the event was dispatched
Its the element that the event originated

Question 8

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

Answer 8

Bubbling

Question 9

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

Answer 9

Element tag name; property comes back upperCased

Question 10

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

Answer 10

It takes a valid css selector to match the element and it returns the closest ancestor element or itself; closest searches outwards while query is inward.

Question 11

How can you remove an element from the DOM?

Answer 11

Using the remove method; element.remove()

Question 12

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 12

Add an event listener to its ancestor; event delegation

Question 13

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

Answer 13

It hides its content, does not take any space, outside of the flow.

Question 14

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

Answer 14

It takes a valid css selector and returns true if the element matches the selectors otherwise false

Question 15

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

Answer 15

getAttribute; the value of the attribute we’re trying to get

Question 16

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

Answer 16

After every line of code

Question 17

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

Answer 17

You would need a separate function for each view

Question 18

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

Answer 18

no

Question 19

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

Answer 19

appendChild; parent.appendChild(child)

Question 20

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

Answer 20

Its new attribute and the new value

Question 21

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

Answer 21

First is to create a node(element) and then where you want to place it .

Question 22

What is the textContent property of an element object for?

Answer 22

To change or add text or view current text.

Question 23

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

Answer 23

setAttribute and className

Question 24

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

Answer 24

You can reuse it

Question 25

What event is fired when a user places their cursor in a form control?

Answer 25

focus

Question 26

What event is fired when a user’s cursor leaves a form control?

Answer 26

blur

Question 27

What event is fired as a user changes the value of a form control?

Answer 27

input

Question 28

What event is fired when a user clicks the “submit” button within a <form>?

Answer 28

Submit; it fires on the form event not the submit button

Question 29

What does the event.preventDefault() method do?

Answer 29

tells the user agent that if the event does not get explicitly handled, its default action should not be taken as it normally would be

Question 30

What does submitting a form without event.preventDefault() do?

Answer 30

Your page reloads

Question 31

What property of a form element object contains all of the form’s controls.

Answer 31

Form.elements; the elements property

Question 32

What property of a form control object gets and sets its value?

Answer 32

The value property

Question 33

What is one risk of writing a lot of code without checking to see if it works so far?

Answer 33

Chaos; you won’t know what code will work and what won’t.

Question 34

What is an advantage of having your console open when writing a JavaScript program?

Answer 34

To see if there’s any errors

Question 35

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

Answer 35

You’re able to call it back at any time.

Question 36

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

Answer 36

complicated , we wouldn’t be able to keep track. Ease of access.

Question 37

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

Answer 37

Use the textContent property to change the text of an element

Question 38

What is the textContent property of element objects?

Answer 38

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

Question 39

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

Answer 39

Using className

Question 40

What is the className property of element objects?

Answer 40

gets and sets the value of the class attribute of the specified element.; not a css selector

Question 41

DOM EVENTS

Question 42

Why do we log things to the console?

Answer 42

To verify data

Question 43

What is the purpose of events and event handling?

Answer 43

This is a block of code (usually a JavaScript function that you as a programmer create) that runs when the event fires.register different event handlers on elements in an HTML document