JS - Arrays and Functional Methods

Arrays store ordered collections of values. Functional array methods are used to loop, transform, filter, and reduce arrays.

Core Notes

Method	Returns	Use when
`forEach()`	`undefined`	doing something for each item
`map()`	new array	transforming each item
`filter()`	new array	keeping matching items
`reduce()`	one value	accumulating into a total/object/string
`sort()`	sorted original array	ordering items