Objects

Question 1

.keys

Answer 1

Static method returns array of object’s properties
* Enumerable keys only

Array of string-keyed property keys

Object.keys(obj)

Question 2

.values()

Answer 2

Static method returns array of objects values
* Enumerable values only

Array of string-keyed property values

Object.values(obj)

Question 3

.entries()

Answer 3

Static method returns array of property key-value pairs
* Enumerable values only

Array of string-keyed property key-value pairs

Object.entries(obj)

Question 4

.assign()

Answer 4

Copies the values of all enumerable own properties from N source objects to a target object
* Assigns properties, not copying or defining new ones
* Envokes getters & setters

The target object

Object.assign(target, ...sources)

Question 5

.freeze()

Answer 5

Prevents an object from being modified
* Prevents extensions & makes exostomg properties non-writable and non-configurable.
* Cannot be changed
* Properties are made immutable

The object that was passed to the function

Object.freeze(obj)

Question 6

.seal()

Answer 6

Prevents new properties from being added to an object and marks all existing properties as non-configurable
* Prevents extensions
* Static Method
* Makes the object have a fixed set of properties, but values can be mutated

The object being sealed

Object.seal(obj)

Question 7

.is()

Answer 7

Compares two values to determine if they are the same value
* Static method
* Not like strict equality operator, b/c it treats signed zeros and Nan differently

A boolean indicating whether or not the two arguments are the same value

Object.is(value1, value2)

Question 8

.hasOwnProperty()

Answer 8

Returns a boolean indicating whether an object has a specific property as a direct property of that object
* As opposed to inheriting it
* Can be called on most JS objects, due to inheritice on most data structures

Returns true if the object has the specified property

Object.prototype.hasOwnProperty(prop)

Question 9

.create()

Answer 9

Creates a new object with a specified prototype object and properties

A new object with teh specified prototype object and properties

Object.create(proto)

Question 10

.defineProperty()

Answer 10

Adds a new property to an object or modifies an exising one
* Properties added using this are not writable enumerable or configurable
* Research this one

The object that was passed to the function

Object.defineProperty(obj, prop, descriptor)