Section 17

Udemy Web Developer Bootcamp Section 17

JavaScript Arrays

JS Arrays are a data structure.
A data structure simply is a collection of data(boolean value, strings).
A data structures, specifically arrays which we're about to see, allow us to group data together ans we could store different strings.

let students = [];

let colors = ["red", "orange", "yellow"];

Modifying Arrays

Unlike with the string, it is possible to change particular characters in an array.

Array Methods

Push : array.push('item')Add to end
String remains unchanged, but with arrays when I push onto array, array actually is updated and what it returns is the technical term is the new length of the array.

Pop : array.pop()remove from end

Shift : array.shift()Remove from start

Unshift : array.unshift('item')Add to start

More Methods
- concat : merge arrays array1.concat(array2)- includes : look for a value array.includes('item')- indexOf : just like string.indexOf array.indexOf('index')- join : creates a string from an array
- reverse : reverses an array array.reverse()- slice : copies a portion on an array array.slice(start, end)- splice : removes/replaces elements array.splice(start, deleteCount, 'item')- sort : sorts an array array.sort()

Reference Types & Equality Testing

JS actually doesn't care about what's inside, at least with arrays.

So when I make a new array ans it has its own address, its own reference, its own social security number.
Even if the contents are the same, they are distinct because the social security numbers are different.

They are the same exact reference. But it's not going to help us if we're trying to compare the contents.

Const & Array

But as soon as I try and set arrays to something entirely defferent, a new reference, we get an error.

Multi-Dimensional Arrays