JS and React.js

Question 1

Linting

Answer 1

Software that screens code for syntax errors while differentiating various elements of code

Question 2

I.D.E.

Answer 2

Integrated Development Environment

Question 3

D.O.M.

Answer 3

Document Model Object

Question 4

What must every component do?

Answer 4

*Render some code to the DOM

Question 5

What 3 arguments are accepted by .createElement?

Answer 5

1) HTML Element
2) Configuration (JS object)
3) Children of Element

Question 6

Var vs Const

Answer 6

Var: can change
Const: data never changes

Question 7

Functional Components are written

Answer 7

const cmp = () => { return <div>some JSX</div> }

Question 8

Class Components are written

Answer 8

class Cmp extends Component 
   { render () 
      { return <div>some JSX</div> } 
   }

Question 9

Dynamic Code within a JSX Element must be wrapped in?

Answer 9

Single curly braces:

{ dynamic code }

Question 10

Children

Answer 10

Any Element that is contained between a Components opening and closing tags

Question 11

Props

Answer 11

Used to dynamically pass code from parent components to child components

Question 12

Dynamic Code

Answer 12

Not hard coded, code easily able to change

Question 13

State

Answer 13

Is managed from within a component and if changed will cause a re-render.

Question 14

Handlers

Answer 14

Class methods that are not actively being called but is triggered by an event

Question 15

Should State should be mutated?

Answer 15

No

Question 16

Mutate

Answer 16

To hard change data

Question 17

How do you inject JS expressions into JSX?

Answer 17

With single curly braces { }

Question 18

Turnery Operator

Answer 18

? = (if) 
\: = (else)

Question 19

.Map( ) does what?

Answer 19

Executes a method on an array

Question 20

Where is JSX written in React projects

Answer 20

After the Return

Question 21

Where is JS written in React projects

Answer 21

After the Render

Question 22

To properly use .Map( ) in needs to be placed on which Element?

Answer 22

The outer most Element

Question 23

What is a good file structure for a React App?

Answer 23

Src >
Components > (Components)
Assets > (Images)

Question 24

What is special about PureComponents

Answer 24

They have shouldComponentUpdate checks built in

Question 25

What is a HOC?

Answer 25

A Higher Order Component

Question 26

What is the proper way to update State within a setState call?

Answer 26

setState( ( prevState, props ) => { return {
statefulElement: prevState.method }
}
)

Question 27

How do ‘Switch’ statements work?

Answer 27

Switch statements take an expression which is evaluated against a set of CASEs to look for the first CASE with the matching expression. If no CASE matches the provided expression then a DEFAULT case is executed. Switch statements fun until a BRAKE is encountered. If more than one CASE matches the Switch will execute the first match and its associated statements.

Question 28

How should you name Global Constants?

Answer 28

In all CAPS and with _ between words.

Question 29

withRouter( ) gives you access to witch 3 methods?

Answer 29

.match( ), .history( ), and .location( )

Question 30

What is “escaping” in JS?

Answer 30

Escaping is using a / to tell the computer that the symbol coming after the backslash is to be interpreted as a string not as a operational value.

Question 31

What are the 6 JavaScript values?

Answer 31

1) Strings
2) Numbers
3) Booleans
4) Objects
5) Functions
6) Undefined

Question 32

What is an “Expression”?

Answer 32

An expression is a combination of values that are computed by the computer. An Expression results in a value.

Question 33

What is a “Statement”?

Answer 33

Statements are computer instructions. A Statement preforms a task.

Question 34

What are semi-colons used for in JS?

Answer 34

A semi-colon is used to separate statements.

Question 35

What is a Function?

Answer 35

A function is a repeatable block of code that executes certain actions and preforms tasks. You execute a function by calling it. This is also know as invoking the function.

Question 36

Koans

Answer 36

code learning website

Question 37

What does the Modulus operator do?

Answer 37

Returns the amount left over after a division.