Javascript - The definitive guide - David Flanagan - Arrays Chapter

jdfArrays.js

/**
* Theory:
  -Arrays in JavaScript are an ordered collection of values
  -Its elements are untyped, an array can contain different types of data
  -Arrays are 32-bit indexed so its index can be from 0-4294967294 (2^32 - 2)
  and its elements can go from 0 to 4.294.967.295
*/

/**
* Relevant Examples
*/
// Dynamic Sizing
let names = ["Anibal", "Peter"]
console.log(names.length) // 2
names[10] = "Lucas"
console.log(names.length) // 11

//Creating arrays
let literalArray = [1,2,3]
let spreadOperatorArrays = [...literalArray] // copy of [1,2,3]
let arrayConstructor = new Array()
let arrayOf = Array.of(1,2,3) // [1,2,3]
let arrayFrom = Array.from(literalArray) // copy of [1,2,3]

// Creating and Updating at the same time
let rankings = [0, 100, 40, 20, 40, 343, 32, 22]
let copy = Array.from(rankings, (r) => r % 10 === 0 ? r : 0)
console.log(copy) // [0, 100, 40, 20, 40, 0, 0, 0]

// Some and Every
let yearTemperature = [40, 44, 40, 34, 30, 28, 26, 25, 28, 39, 35, 38]
console.log(yearTemperature.some((temp) => temp > 40)) // There is at least one element over 40 degrees
console.log(yearTemperature.every((temp) => temp % 2)) // false - not every number is mod 2

// Find and FindIndex
let yearTemperature = [40, 44, 40, 34, 30, 28, 26, 25, 28, 39, 35, 38]
console.log(yearTemperature.find((temp) => temp === 40)) // 40 the first value
console.log(yearTemperature.findIndex((temp) => temp === 40)) // 0 the first encountered





/* End*/