Chapter 3

Question 1

what are the two roles of the … operator?

Answer 1

rest and spread

Question 2

what are the two options in which the spread operator can be used?

Answer 2

in an array or as an argument function call
const test = […testArray];
or
testFunction(…test)

Question 3

iterable

Answer 3

a value that can be iterated over

Question 4

what is the iterator-consumption protocol used for?

Answer 4

consuming iterables

Question 5

how does the iterator-consumption protocol work?

Answer 5

automatically creates an iterator instance from an iterable, and consumes just that iterator instance to its completion. This means a single iterable could be consumed more than once; each time, a new iterator instance would be created and used.

Question 6

what is an iterator protocol?

Answer 6

a standard way to produce a sequence of values (either finite or infinite), and potentially a return value when all values have been generated.

Question 7

how does iteration work on Maps?

Answer 7

it iterates over its entries not its values, and each entry has a value and a key

Question 8

how can we get the index and value in an array iteration?

Answer 8

for (let [idx,val] of arr.entries()) {…}

Question 9

default iteration

Answer 9

each type of iteration has a main or default iteration method, but also exposes other methods if different data needs to be accessed

Question 10

in js what are the main iterator forms that are usually available on any given built-in iterables?

Answer 10

• keys-only (keys())
• values-only (values())
• entries (entries())

Question 11

Closure

Answer 11

is when a function remembers and continues to access variables from outside its scope, even when the function is executed in a different scope

Question 12

what is the difference between scope and execution context?

Answer 12

Scope is static and is comprised of the variables available at the time and location that you defined the function

The execution context is dynamic and dependent on how it is called

Question 13

what does the call method do?

Answer 13

binds the execution context the specified object

someObject.call(someFunction)

Question 14

what is another word of/way we reference this?

Answer 14

execution context

Question 15

prototype chain

Answer 15

A series of objects linked together via prototypes

Question 16

What is the purpose of prototype linkage?

Answer 16

accesses against B for properties/methods that B does not have, are delegated to A to handle.

ie. Delegation of property/method access allows two (or more!) objects to cooperate with each other to perform a task.

Question 17

How can you define an object prototype linkage?

Answer 17

you can create the object using the Object.create(..) utility

let otherHomework = Object.create(homework);

Question 18

what does Object.create(null) do?

Answer 18

creates an object that is not prototype linked anywhere, so it’s purely just a standalone object