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LearningFuze > Study Cards > Flashcards

Study Cards Flashcards

1
Q

Where do you put non-visible content about the HTML document?

A

In the head element.

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2
Q

Where do you put visible content about the HTML document?

A

In the body element.

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3
Q

Where do the head and body tags go in a valid HTML document?

A

In the html element.

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4
Q

What is the purpose of a !DOCTYPE declaration?

A

To instruct the web browser what document type to expect.

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5
Q

What is the purpose of HTML attributes?

A

To provide additional information about the contents of an element.

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6
Q

How do block-level elements affect the document flow?

A

Always appear on a new line, and take up the entire horizontal space of their parent element.

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7
Q

How do inline elements affect the document flow?

A

Continue on the same line as neighboring elements.

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8
Q

What are the default width and height of a block-level element?

A

Width: Entire horizontal space of its parent element.
Height: Height of its contents.

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9
Q

What are the default width and height of an inline element?

A

The width and height of its contents.

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10
Q

What is the difference between an ordered list and an unordered list in HTML?

A

Ordered list items are numbered, unordered list items are not.

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11
Q

Is an HTML list a block element or an inline element?

A

Block.

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12
Q

What HTML tag is used to link to another website?

A

a tag

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13
Q

What is an absolute URL?

A

The full web address.

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14
Q

What is a relative URL?

A

A shorthand link address for a page within the same site.

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15
Q

How do you indicate the relative link to a parent directory?

A

../

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16
Q

How do you indicate the relative link to a child directory?

A

The name of the directory.

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17
Q

How do you indicate the relative link to a grand parent directory?

A

../../

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18
Q

How do you indicate the link to the same directory?

A

Simply use the name of the target file.

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19
Q

What is the purpose of an HTML form element?

A

To allow users to submit data.

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20
Q

Give five examples of form control elements.

A

buttons, checkboxes, radio buttons, text input, select lists

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21
Q

Give three examples of type attributes for HTML < input > elements.

A

text, email, password, radio, checkbox, submit

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22
Q

Is an HTML < input > element a block or inline element?

A

inline

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23
Q

What are the six primary HTML elements for creating tables?

A

< table >, < thead >, < tbody >, < tr >, < th >, < td >

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24
Q

What purpose do the thead and tbody elements serve?

A

Differentiate between the headers and the general table data.

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25
Q

Give two examples of data that would lend itself well to being displayed in a table.

A

Stocks, sports statistics, etc.

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26
Q

What are the names of the individual pieces of a CSS rule?

A

Selector, curly braces which define the declaration block, and property/value pairs.

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27
Q

In CSS, how do you select elements by their class attribute?

A

With a .classname

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28
Q

In CSS, how do you select elements by their type?

A

The name of the element

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29
Q

In CSS, how do you select an element by its id attribute?

A

With a #idname

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30
Q

Name three different types of values you can use to specify colors in CSS.

A

Color names, RGB values, HEX codes

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31
Q

What CSS properties make up the box model?

A

Content, padding, border, and margin.

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32
Q

Which CSS property pushes boxes away from each other?

A

Margin

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33
Q

Which CSS property adds space between a box’s content and its border?

A

Padding

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34
Q

What is a pseudo-class?

A

A keyword added to a selector that specifies a special state of the selected element(s), like :hover or :visited

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35
Q

What are pseudo-classes useful for?

A

Allow you to apply style not just to the content, but in relation to the status of content items, like :hover, :visited, :checked etc.

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36
Q

What CSS property controls the font used for the text inside an element?

A

font-family

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37
Q

What is the default flex-direction of a flex container?

A

row

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38
Q

What is the default flex-wrap of a flex container?

A

no-wrap

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39
Q

Why do two div elements “vertically stack” on one another by default?

A

They are block level elements by default

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40
Q

What is the default flex-direction of an element with display: flex?

A

row

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41
Q

What is the default value for the position property of HTML elements?

A

static

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42
Q

How does setting position: relative on an element affect document flow?

A

It doesn’t

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43
Q

How does setting position: relative on an element affect where it appears on the page?

A

It doesn’t

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44
Q

How does setting position: absolute on an element affect document flow?

A

It removes the element from the document flow.

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45
Q

How does setting position: absolute on an element affect where it appears on the page?

A

The element will be positioned relative to its first non-static parent element (usually with a position: relative)

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46
Q

What is the main purpose of using position: absolute?

A

Layering elements on top of other elements.

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47
Q

How do you constrain an absolutely positioned element to a containing block?

A

Give a parent element a position: relative

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48
Q

What are the four box offset properties?

A

top, bottom, left, right

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49
Q

What is the purpose of variables?

A

To store data for later use.

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50
Q

How do you declare a variable?

A

const or let variableName = value;

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51
Q

How do you initialize (assign a value to) a variable?

A

with const or let keyword variableName = value

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52
Q

What characters are allowed in variable names?

A

Letter, number, underscore. The first character CANNOT be a number.

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53
Q

What does it mean to say that variable names are “case sensitive”?

A

References to a variable must be made using the identical case/capitalization as the variable declaration.

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54
Q

What is the purpose of a string?

A

To hold data that can be represented in text form.

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55
Q

What is the purpose of a number?

A

To save a number to be used in mathematical calculation.

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56
Q

What is the purpose of a boolean?

A

Useful when the data can only have two possible values, true or false.

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57
Q

What does the = operator mean in JavaScript?

A

assignment

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58
Q

How do you update the value of a variable?

A

variableName = newValue; (var keyword only to be used during initial variable creation)

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59
Q

What is the difference between null and undefined?

A

null is an empty value, undefined means no value has been assigned

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60
Q

Why is it a good habit to include “labels” when you log values to the browser console?

A

Clarifies what data is being logged to the console.

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61
Q

Give five examples of JavaScript primitives

A

string, number, boolean, null, undefined

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62
Q

What data type is returned by an arithmetic operation?

A

number

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63
Q

What is string concatenation?

A

appending one string to the end of another string

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64
Q

What purpose(s) does the + plus operator serve in JavaScript?

A

addition operator and concatenation operator

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65
Q

What data type is returned by comparing two values (greater than/less than operator, ===, etc)?

A

Boolean

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66
Q

What does the += “plus-equals” operator do?

A

Adds the provided value to a variable

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67
Q

What are objects used for?

A

Holding data in the form of multiple properties split into key-value pairs.

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68
Q

What are object properties?

A

Data held within objects in the form of key-value pairs

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69
Q

Describe object literal notation.

A

A set of curly braces with key-value pairs contained within

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70
Q

How do you remove a property from an object?

A

with the delete operator (delete objectName.propertyName)

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71
Q

What are two ways to get or update the value of a property?

A

Dot notation (objectName.propertyName) (preferred) and bracket notation (objectName[“propertyName”])

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72
Q

What are arrays used for?

A

Holding lists of related data in an ordered format.

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73
Q

Describe array literal notation.

A

A set of brackets with values separated by commas.

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74
Q

How are arrays different from “plain” objects?

A

They are ordered, and contain values at numbered indexes rather than key-value pairs

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75
Q

What number represents the first index of an array?

A

0

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76
Q

What is the length property of an array?

A

Determines the number of values contained in the array

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77
Q

How do you calculate the last index of an array?

A

array.length - 1

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78
Q

What is a function in JavaScript?

A

A set of “instructions”, whose code can be saved and called for later use

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79
Q

Describe the parts of a function definition.

A

The function keyword, the function name (optional), parameters in parentheses (optional), and the code block contained by curly braces. Often a return statement is included in the code block.

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80
Q

Describe the parts of a function call.

A

The name of the function and parentheses, as well as any arguments in the parentheses if necessary

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81
Q

When comparing them side-by-side, what are the differences between a function call and a function definition?

A

Function definition includes function keyword and code block, which are not used in function call

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82
Q

What is the difference between a parameter and an argument?

A

Parameter is a placeholder used in a function definition, argument is the actual data passed to the function in a function call.

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83
Q

Why are function parameters useful?

A

Allows us to pass different data to functions, to use the same function to perform different tasks.

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84
Q

What two effects does a return statement have on the behavior of the function?

A

The function will produce a value, and prevents any more code in the function’s code block from being run.

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85
Q

Why do we log things to the console?

A

To check our work during the development phase

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86
Q

What is a method?

A

A function which is a property of an object

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87
Q

How is a method different from any other function?

A

A method is a function which is a property of an object, rather than just a free-floating function

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88
Q

How do you remove the last element from an array?

A

the .pop() method

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89
Q

How do you round a number down to the nearest integer?

A

the Math.floor() method

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90
Q

How do you generate a random number?

A

the Math.random() method

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91
Q

How do you delete an element from an array?

A

.unshift() will remove an element from the beginning of an array;
.pop() will remove an element from the end of an array;
.splice() can remove an element from a specified index of an array

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92
Q

How do you append an element to an array?

A

.shift() will add an element to the beginning of an array;
.push() will add an element to the end of an array;
.splice() can add an element to a specified index of an array

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93
Q

How do you break a string up into an array?

A

the .split() method

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94
Q

Is the return value of a function or method useful in every situation?

A

No, sometimes the return value is not needed

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95
Q

What three-letter acronym should you always include in your Google search about a JavaScript method or CSS property?

A

MDN

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96
Q

Give 6 examples of comparison operators?

A

Equal, strictly equal, not equal, strictly not equal, less than, greater than, less than or equal to, greater than or equal to

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97
Q

What data type do comparison expressions evaluate to?

A

Boolean

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98
Q

What is the purpose of an if statement?

A

To determine whether or not to run code based on a condition

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99
Q

Is else required in order to use an if statement?

A

No

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100
Q

Describe the syntax of an if statement

A

if (condition) {

}

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101
Q

What are three logical operators?

A

and (&&), or (||), and not (!)

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102
Q

What is the purpose of a loop?

A

To require code to be repeated

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103
Q

What is the purpose of a condition expression in a loop?

A

Determine whether or not the code should be run again

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104
Q

What does “iteration” mean in the context of loops?

A

Each time the loop is run, ie every time the condition is tested, the code is run, and the final expression is executed

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105
Q

When does the condition expression of a while loop get evaluated?

A

Every iteration before the code block is run

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106
Q

When does the initialization expression for a for loop get evaluated?

A

At the beginning of the for loop, the first time the loop is run

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107
Q

When does the condition expression for a for loop get evaluated?

A

After the initialization, and on every iteration before the code block is run

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108
Q

When does the final expression of a for loop get evaluated?

A

Every iteration after the code block is run, and before the condition is evaluated

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109
Q

Besides a return statement, which exits its entire function block, which keyword exits a loop before its condition expression evaluates to false?

A

break

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110
Q

What does the ++ increment operator do?

A

Increases the value of the variable by 1

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111
Q

How do you iterate through the keys of an object?

A

for…in loop

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112
Q

What are the 4 components of the CSS cascade?

A

source order, inheritance, specificity, and !important

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113
Q

What does the term “source order” mean with respect to CSS?

A

The styling provided for an element LAST in the stylesheet is the styling that will be applied

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114
Q

How is it possible for the styles of an element to be applied to its children as well without an additional CSS rule?

A

Inheritance

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115
Q

List the three selector types in order of increasing specificity

A

element, class, id

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116
Q

Why is using !important considered bad practice?

A

It overrides other declarations and breaks the natural cascading of stylesheets

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117
Q

Why do we log things to the console?

A

To show data of what our code is doing for use in the development phase.

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118
Q

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

A

The actual html page that is being modeled in JavaScript

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119
Q

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

A

A JavaScript object, which is being used to model the html document

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120
Q

What is a DOM Tree?

A

The model of the web page with parent/child relationships, created by the DOM.

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121
Q

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

A

.querySelector(), .getElementById()

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122
Q

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

A

.querySelectorAll()

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123
Q

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

A

Makes it easier to access that DOM query later.

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124
Q

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

A

console.dir()

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125
Q

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

A

So the code before it will run, which will allow us to make changes to that code in the .js file referenced by our script tag

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126
Q

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

A

It takes a CSS selector as its argument, and returns the FIRST element that matches that description

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127
Q

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

A

It takes a CSS selector as its argument, and returns ALL elements that match that description

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128
Q

What is the purpose of events and event handling?

A

To allow JavaScript to make changes when a user interacts with the page

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129
Q

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

A

Optional

130
Q

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

A

.addEventListener()

131
Q

What is a callback function?

A

A previously defined function that is used later in the code

132
Q

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

A

The event

133
Q

What is the event.target?

A

The object on which the event is occuring

134
Q

What is the className property of element objects?

A

allows us to access or change the class of an element

135
Q

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

A

.className property

136
Q

What is the textContent property of element objects?

A

allows us to access or change the text content of an element

137
Q

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

A

.textContent property

138
Q

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

A

No, sometimes it is not needed in the callback function

139
Q

What does the CSS transform property do?

A

Changes how an element is displayed visually (including translate(), scale(), rotate(), skew(), and matrix() )

140
Q

The transition property is shorthand for which four CSS properties?

A

transition-property, transition-duration, transition-timing-function, and transition-delay

141
Q

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

A

focus

142
Q

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

A

blur

143
Q

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

A

input

144
Q

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

A

submit

145
Q

What does the event.preventDefault() method do?

A

Prevents the browser from refreshing

146
Q

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

A

elements

147
Q

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

A

value

148
Q

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

A

The more code you write without checking, the more code you will have to check through to see where the error is coming from.

149
Q

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

A

You can check your code as you go

150
Q

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

A

No, it only creates the element in JavaScript, it needs to be inserted into the page with a method such as appendChild()

151
Q

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

A

appendChild() method

152
Q

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

A

(‘attributename’, ‘value’)

153
Q

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

A

Create the element with something like createElement(), insert with something like appendChild()

154
Q

What is the textContent property of an element object for?

A

getting and setting the text content of an element

155
Q

Name two way to set the class attribute of a DOM element

A

setAttribute() method and className property

156
Q

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

A

It is reusable and makes grouping/structure more clean and logical

157
Q

Give two examples of media features that you can query in a @media rule

A

width, height, resolution, orientation, aspect-ratio, many more…

158
Q

Which HTML meta tag is used in mobile-responsive web pages?

A
159
Q

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

A

Bubbling. By default events “bubble”, or propagate through the chain of their ancestor elements

160
Q

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

A

event.target.tagName

161
Q

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

A

It takes a selector as its argument and returns the closest ancestor element matching that criteria

162
Q

How can you remove an element from the DOM?

A

remove()

163
Q

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?

A

Target a parent containing element and utilize DOM event delegation

164
Q

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

A

It is completely removed from the page and document flow, as if it did not exist

165
Q

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

A

It takes a selector as its argument and returns a boolean indicating whether or not it is a match

166
Q

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

A

getAttribute()

167
Q

What is a breakpoint in responsive Web design?

A

The size at which a website’s style properties will change to adapt to the screen size

168
Q

What is the advantage of using a percentage width instead of a fixed width for a “column” class in a responsive layout?

A

The percentage is relative and will resize based on the size of the browser window

169
Q

If you introduce CSS rules for a smaller min-width after the styles for a larger min-width in your style sheet, the CSS rules for the smaller min-width will “win”. Why is that?

A

Because of the Source-Order of CSS

170
Q

What is JSON?

A

a text-based data format following JavaScript object syntax

171
Q

What are serialization and deserialization?

A

Converting data (objects, etc) into bytes (a string in the case of JSON) to be transmitted

172
Q

How do you serialize a data structure into a JSON string using JavaScript?

A

.stringify() method

173
Q

How do you deserialize a JSON string into a data structure using JavaScript?

A

.parse() method

174
Q

What method do you use to store data in localStorage?

A

.setItem()

175
Q

What method do you use to retrieve data in localStorage?

A

.getItem()

176
Q

What data type can localStorage save in the browser?

A

string

177
Q

When does the ‘beforeunload’ event fire on the window object?

A

When the page is refreshed, closed, or unloaded in some way

178
Q

What is a method?

A

A function that is a property of an object

179
Q

How can you tell the difference between a method definition and a method call?

A

A method call will include .methodname()

180
Q

What is the defining characteristic of Object-Oriented Programming (OOP)?

A

objects can contain both data (as properties) and behavior (as methods)

181
Q

What is abstraction?

A

being able to work with (possibly) complex things in simple ways

182
Q

What does API stand for?

A

application programming interface

183
Q

What is the purpose of an API?

A

defines interactions between multiple software intermediaries. A set of rules that allow programs to talk to each other

184
Q

What is ‘this’ in JavaScript?

A

An implicit parameter of an object

185
Q

What does it mean to say that this is an “implicit parameter”?

A

it is available in a function’s code block even though it was never included in the function’s parameter list or declared

186
Q

When is the value of this determined in a function; call time or definition time?

A

call time

187
Q

How can you tell what the value of this is for a particular function or method call?

A

The object to the left of the dot

188
Q

What kind of inheritance does the JavaScript programming language use?

A

Prototype-based inheritance

189
Q

How is it possible to call methods on strings, arrays, and numbers even though those methods don’t actually exist on objects, arrays, and numbers?

A

With prototypes

190
Q

If an object does not have it’s own property or method by a given key, where does JavaScript look for it?

A

In the prototype object

191
Q

What does the new operator do?

A

Create a new instance of the object type specified by the constructor function

192
Q

What property of JavaScript functions can store shared behavior for instances created with new?

A

prototype

193
Q

What does the instanceof operator do?

A

Determines whether the specified object is an instance of the specified constructor. Returns a boolean value.

194
Q

Besides adding an event listener callback function to an element or the document, what is one way to delay the execution of a JavaScript function until some point in the future?

A

setTimeout()

195
Q

How can you set up a function to be called repeatedly without using a loop?

A

setInterval()

196
Q

What is the default time delay if you omit the delay parameter from setTimeout() or setInterval()?

A

0 (execute immediately)

197
Q

What do setTimeout() and setInterval() return?

A

The timer ID (a positive integer). Can be passed to clearTimeout() to cancel the timer

198
Q

What is a code block? What are some examples?

A

The code contained within a set of curly braces in a function, if statement, loop

199
Q

What does block scope mean?

A

A block scope variable can only be accessed in the code block where it is declared

200
Q

What is the scope of a variable declared with const or let?

A

Block scope

201
Q

What is the difference between let and const?

A

let can be reassigned, const cannot

202
Q

Why is it possible to .push() a new value into a const variable that points to an array?

A

Because in a const variable, the value cannot be reassigned but if the value is an object or an array, it can be mutated

203
Q

How should you decide which type of variable declaration to use?

A

const unless a variable will need to be reassigned, then use let

204
Q

What is destructuring, conceptually?

A

Makes it possible to unpack values from arrays, or properties from objects, into distinct variables

205
Q

What is the syntax for object destructuring?

A

const { property1, property2 } = objectName

206
Q

What is the syntax for array destructuring?

A

const [ element1, element2 ] = arrayName

207
Q

How can you tell the difference between destructuring and creating object/array literals?

A

By identifying which side of the assignment operator the braces/brackets are on

208
Q

What is the syntax for writing a template literal?

A

Surround in backticks (``), javascript expressions contained in ${}

209
Q

What is string interpolation?

A

Replacing placeholders with values in a string literal

210
Q

What is the syntax for defining an arrow function?

A

(parameter1, parameter2) => { code block }

211
Q

When an arrow function’s body is left without curly braces, what changes in its functionality?

A

The function will automatically return the result of the expression to the right of the arrow

212
Q

How is the value of ‘this’ determined within an arrow function?

A

It derives the value of ‘this’ from the scope where it was created

213
Q

What is Node.js?

A

An asynchronous event-driven JS runtime, which allows JS to be run outside of a web browser

214
Q

What can Node.js be used for?

A

To build back ends for web apps, command-line programs, or develop other automation

215
Q

What is a REPL?

A

Read-eval-print loop

216
Q

What is a CLI?

A

Command line interface

217
Q

What is a GUI?

A

Graphical user interface

218
Q

What is a computer process?

A

An instance of a computer program that is being executed

219
Q

What is the process object in a Node.js program?

A

A global object the provides info and control over the current Node.js process

220
Q

How do you access the process object in a Node.js program?

A

It is a global object, so using “process”

221
Q

What is the data type of process.argv in Node.js

A

Array

222
Q

What is a JavaScript module?

A

A single JavaScript file

223
Q

What values are passed into a Node.js module’s global scope?

A

exports, module, require(), __dirname, __filename

224
Q

What is the purpose of module.exports in a Node.js module?

A

To access a module’s code from a different module

225
Q

How do you import functionality into a Node.js module from another Node.js module?

A

require()

226
Q

What is the javascript event loop?

A

Monitors the Call Stack and Callback Queue. When the Stack is empty, it will take the first event from the Queue and push it to the Stack

227
Q

What is different between blocking and non-blocking with respect to how code is executed?

A

Blocking is when the execution of additional code must wait until the operation completes

228
Q

What module does Node.js include for manipulating the file system?

A

fs

229
Q

What method is available in the Node.js fs module for writing data to a file?

A

writeFile()

230
Q

Are file operations using the fs module synchronous or asynchronous?

A

There are asynchronous and synchronous operations

231
Q

Which HTTP method does a browser issue to a web server when you visit a URL?

A

GET

232
Q

What is on the first line of an HTTP request message?

A

The request method (get, post, etc), target, and HTTP standard (HTTP/1.1)

233
Q

What is on the first line of an HTTP response message?

A

The HTTP standard (HTTP/1.1), status code, and status message

234
Q

What are HTTP headers?

A

Additional information passed with an HTTP request or response

235
Q

Is a body required for a valid HTTP message?

A

No

236
Q

What is npm?

A

A service comprised of a website, command line interface, and registry of code packages that can be utilized

237
Q

What is a package?

A

A directory containing code files, as well as a package.json file.

238
Q

How can you create a package.json with npm?

A

npm init –yes

239
Q

What is a dependency and how do you add one to a package?

A

A dependency is a package that is required to use another package. You can add one with npm install packagename

240
Q

What happens when you add a dependency to a package with npm?

A

The package and all the package’s dependencies are added to the node-modules directory, and the dependency is added to the dependencies object in package.json

241
Q

How do you add express to your package dependencies?

A

npm install express

242
Q

What Express application method starts the server and binds it to a network PORT?

A

.listen()

243
Q

How do you mount a middleware with an Express application?

A

.use()

244
Q

Which objects does an Express application pass to your middleware to manage the request/response lifecycle of the server?

A

request and response objects

245
Q

What is the appropriate Content-Type header for HTTP messages that contain JSON in their bodies?

A

application/json

246
Q

What is the significance of an HTTP request’s method?

A

It is purely semantic, all requests have the same functionality

247
Q

What does the express.json() middleware do?

A

Automatically parses incoming requests with JSON

248
Q

What is PostgreSQL and what are some alternatives?

A

A relational database. Other relational databases: MySQL, Oracle, Microsoft SQL Server…

249
Q

What are some advantages of learning a relational database?

A

Ideal for storing related data. Make data corruption as unlikely as possible.

250
Q

What is one way to see if PostgreSQL is running?

A

sudo service postgresql status

251
Q

What is a database schema?

A

A collection of tables. Defines how the data in a relational database should be organized

252
Q

What is a table in a relational database?

A

A list of rows, each having the same set of attributes

253
Q

What is a row in a relational database?

A

An instance of a record

254
Q

What is SQL and how is it different from languages like JavaScript?

A

Structured Query Language. Used for managing data in relational databases. Operates through simple, declarative statements.

255
Q

How do you retrieve specific columns from a database table?

A

select keyword with columns in double quotes

256
Q

How do you filter rows based on some specific criteria?

A

where keyword with comparison operators

257
Q

What are the benefits of formatting your SQL?

A

Consistency and readability

258
Q

What are four SQL comparison operators that can be used in a where clause?

A

=, , >+, <=, <> (not equal)

259
Q

How do you limit the number of rows returned in a database result set?

A

Limit keyword with number

260
Q

How do you retrieve all columns from a database table?

A

*

261
Q

How do you control the sort order of a result set?

A

order by “”

262
Q

How do you add a row to a SQL table?

A

insert into “tablename” (“columns” separated by commas)

values (‘correspondingvalues’ separated by commas)

263
Q

What is a tuple?

A

A list of values in SQL

264
Q

How do you add multiple rows to a SQL table at once?

A

Specify more than one tuple of values, separated by commas

265
Q

How do you get back the row being inserted into a table without a separate select statement?

A

returning *

266
Q

How do you update rows in a database table?

A

update “tablename”

set “columnname” = ‘value’

267
Q

Why is it important to include a where clause in your update statements?

A

So you don’t update EVERY row in the table

268
Q

How do you delete rows from a database table?

A

delete from “tablename”

where “columnname” = ‘value’

269
Q

How do you accidentally delete all rows from a table?

A

delete from “tablename”

without specifying a where statement

270
Q

What is a foreign key?

A

A table column that refers to values in another table

271
Q

How do you join two SQL tables?

A

After from statement, use:

join “tablename” using (“connectioncolumnname”)

272
Q

How do you temporarily rename columns or tables in a SQL statement?

A

select “columnname” as “aliasname”

273
Q

What are some examples of aggregate functions in SQL?

A

sum(), count(), avg(), max(), min(), every()

274
Q

What is the purpose of a group by clause in SQL?

A

Allows you to separate rows into groups and performs aggregate functions on these groups

275
Q

What are the three states a Promise can be in?

A

pending, fulfilled, rejected

276
Q

How do you handle the fulfillment of a Promise?

A

.then() method, with fulfillment handler function passed in

277
Q

How do you handle the rejection of a Promise?

A

.catch() method, with rejection handler function passed in

278
Q

What is Array.prototype.filter useful for?

A

Creating a new array with all elements that pass the test in the provided function

279
Q

What is Array.prototype.map useful for?

A

Creating a new array with the results of calling a provided function on every element in an array

280
Q

What is Array.prototype.reduce useful for?

A

Executes a function on each element of an array, returning a single output value

281
Q

What is “syntactic sugar”?

A

Functions the same, but looks better/cleaner

282
Q

What is the typeof an ES6 class?

A

Function

283
Q

Describe ES6 class syntax

A

class functionName {}

284
Q

What is “refactoring”?

A

Restructuring existing code without changing its external behavior, with the intention of improving it

285
Q

What is Webpack?

A

A tool to bundle JavaScript applications/modules

286
Q

How do you add a devDependency to a package?

A

npm install packagename –save-dev

287
Q

What is an npm script?

A

npm scripts can automate repetitive tasks. Located in package.json

288
Q

How do you execute Webpack with npm run?

A

Add “build”: “webpack” script in package.json, and use command npm run build

289
Q

What is React?

A

A component-based JavaScript library for building interactive user interfaces

290
Q

What is a React element?

A

An object created with React.createElement that describes what you will see on the screen.

291
Q

How do you mount a React element to the DOM?

A

ReactDOM.render(element, container[, callback])

292
Q

What is Babel?

A

A JavaScript compiler used to covert ES6 code into a backwards compatible version of JavaScript

293
Q

What is a Plug-in?

A

A software component that adds an additional feature to an existing program

294
Q

What is a webpack loader?

A

Transforms source code of a module before they are loaded

295
Q

How can you make babel and webpack work together?

A

With babel-loader

296
Q

What is JSX?

A

A syntax extension to JavaScript, used with React

297
Q

Why must the React object be imported when authoring JSX in a module?

A

When we are using JSX, it is implicitly using React methods.

298
Q

How can you make Webpack and Babel work together to convert JSX into valid JavaScript?

A

Use the babel loader and @babel/plugin-transform-react-jsx to convert the JSX to JavaScript when the files are combined into main.js by webpack

299
Q

What is a React component?

A

They are reusable bits of code that work in isolation and return HTML via a render function. Either a function or a class

300
Q

How do you define a function component in React?

A 
function Name(props) {
  return 
}
301
Q

How do you mount a React component to the DOM?

A

With ReactDOM.render() method

302
Q

What are props in React?

A

Properties used for passing data to components

303
Q

How do you pass props to a component?

A

By passing the prop as a key value pair when creating a react element

304
Q

How do you write JavaScript expressions in JSX?

A

Inside curly braces

305
Q

How do you create class components in React?

A

class Name extends React.component {}

306
Q

How do you access props in a React class component?

A

this.props

307
Q

What is the purpose of state in React?

A

Is is data managed WITHIN a component, can be changed over time and used to make changes within the component

308
Q

How to you pass an event handler to a React element?

A

As a prop, prop name is the name of the event in camelCase

309
Q

What are controlled components in React?

A

A form element whose value is controlled by React

310
Q

What two props must you pass to an input for it to be “controlled”?

A

A value prop with corresponding state property as its value, and an onChange event with corresponding handler function as its value

311
Q

What Array method is commonly used to create a list of React elements?

A

map()

312
Q

What is the best value to use as a “key” prop when rendering lists?

A

An ID, or a string that uniquely identifies a list item among its siblings

313
Q

What does express.static() return?

A

A middleware function

314
Q

What is the local __dirname variable in a Node.js module?

A

The directory name of the current module, as a string

315
Q

What does the join() method of Node’s path module do?

A

Joins all given path segments together and normalizes the resulting path

316
Q

What does fetch() return?

A

A promise that resolves to a response object

317
Q

What is the default request method used by fetch()?

A

GET

318
Q

How do you specify the request method (GET, POST, etc.) when calling fetch?

A

Include an optional init object as the second argument, and specify the property method: ‘POST’

319
Q

When does React call a component’s componentDidMount method?

A

Immediately after a component is initially mounted

320
Q

Name three React.Component lifecycle methods.

A

componentDidMount, componentDidUpdate, componentWillUnmount

321
Q

How do you pass data to a child component in React?

A

As props

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