Arrays

General Notes

Array.isArray() was created because there is no typeof property for arrays since they are typeof objects

Weird stuff happens when you use an array constructor for a single item in an array.

const points = new Array(40, 100, 1);
points
[40, 100, 1

const points2 = [40, 100, 1]
points
[40, 100, 1]

const points3 = new Array(40)
points
[ <40 empty items> ]

const points4 = [40]
points
[ 40 ]

Array Methods

Converting Arrays to Strings

.toString() converts an array into a comma separated string

.join(separator) also converts an array into a string and you can specify the separator as a parameter.

JavaScript automatically converts an array to a comma separated string when a primitive value is expected. Without needing to call the .toString() method

Popping and Pushing

.pop(element) removes the last element

.push(element) adds an element to the end of the array

Shifting Elements

.shift() removes the first element and shifts the others to the left, it also returns the element that was shifted out

.unshift() adds a new element at the beginning of the array and returns the new array length

Changing Elements

.length easy way to append an element to an array, also provides the length of an array

delete array[0] will delete the element but leave an undefined hole

.concat() will combine any number of arrays or strings

.splice() can be used to add new items to the array ex:

const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(2, 0, "Lemon", "Kiwi");

.slice(start, end) slices out a piece of an array into a new array but does not modify the old array.

const fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
const citrus = fruits.slice(1);
citrus = [ 'Orange', 'Lemon', 'Apple', 'Mango' ]
fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"]