Manipulating arrays by use case

// 1. The obvious way 😇
const fruits = ['fruit', 'fruit', 'fruit', 'fruit', 'fruit']

// 2. The old fashion way 🥃
const fruits = new Array(5)
for (let i=0; i<test.length; i++) {
  fruits[i] = 'fruit'
}

// 3. Using Array.prototype.fill()
const fruits = new Array(5).fill('fruit')

// 4. Using Array.from()
const fruits = Array.from({length: 5}, () => 'fruit')

// 5. Using spreading
const fruits = [...new Array(5)].map(() => 'fruit')

// 6. Using concat
const fruits = ['fruit', 'fruit', 'fruit'].concat(['fruit', 'fruit'])

const fruits = [
  { name: "apple", quantity: 3 },
  { name: "orange", quantity: 5 },
  { name: "pear", quantity: 1 },
  { name: "banana", quantity: 0 },
]

// 1. Transform with Array.prototype.map()
fruits.map(fruit => fruit.name)
// > [ 'apple', 'orange', 'pear', 'banana' ]

fruits.map((fruit, idx) => {
    // Map is particularly usefull to build strings for each element of an array
    let str = `#${idx + 1} ${fruit.name} (${fruit.quantity})`
    return str
})
// > ['#1 apple (3)', '#2 orange (5)', '#3 pear (1)', '#4 banana (3)']


// 2. Filter the array
fruits.filter(fruit => fruit.quantity === 0)
// > ['banana']

// 4. "Reduce" the array to a single value
fruits.reduce((total, fruit) => total + fruit.quantity, 0)
// > 9

// 5. Get a "slice" out of the array (without changing it)
fruits.slice(0, 2)
// > [ { name: 'apple', quantity: 3 }, { name: 'orange', quantity: 5 } ]

// The original array is still untouched
console.log(fruits)
// > [
//     { name: "apple", quantity: 3 },
//     { name: "orange", quantity: 5 },
//     { name: "pear", quantity: 1 },
//     { name: "banana", quantity: 0 },
//   ]

// 1. Remove the last item (and return it)
fruits.pop()
// > { name: 'banana', quantity: 3 }
console.log(fruits)
// > [
//     { name: 'apple', quantity: 3 },
//     { name: 'orange', quantity: 5 },
//     { name: 'pear', quantity: 1 }
//   ]

// 2. Add one or more item(s) at the end (return the new length)
fruits.push({name: 'kiwi', quantity: 2}, {name: 'strawberry', quantity: 14})
// > 5
console.log(fruits)
// > [
//     { name: 'apple', quantity: 3 },
//     { name: 'orange', quantity: 5 },
//     { name: 'pear', quantity: 1 },
//     { name: 'kiwi', quantity: 2 },
//     { name: 'strawberry', quantity: 14 }
//   ]

// 3. Remove the first item (and return it)
fruits.shift()
// > { name: 'apple', quantity: 3 },
console.log(fruits)
// > [
//     { name: 'orange', quantity: 5 },
//     { name: 'pear', quantity: 1 },
//     { name: 'kiwi', quantity: 2 },
//     { name: 'strawberry', quantity: 14 }
//   ]

// 4. Add an item at the begining (return the new length)
fruits.unshift({ name: 'cherry', quantity: 7 })
// > 5
console.log(fruits)
// > [
//     { name: 'cherry', quantity: 7 },
//     { name: 'orange', quantity: 5 },
//     { name: 'pear', quantity: 1 },
//     { name: 'kiwi', quantity: 2 },
//     { name: 'strawberry', quantity: 14 }
//   ]

// Array.prototype.splice(index[, deleteCount, element1, ..., elementN])

// 1. Remove elements 
let colors = ['green', 'yellow', 'blue', 'purple'];
colors.splice(0, 2)
// > [ 'green', 'yellow' ] 
console.log(colors)
// > [ 'blue', 'purple' ]

// ... without "deleteCount", all elements starting from "index" are removed
let colors = ['green', 'yellow', 'blue', 'purple'];
colors.splice(1)
// > [ 'yellow', 'blue', 'purple' ]
console.log(colors)
// > [ 'green' ]

// 2. Replace elements
let colors = ['green', 'yellow', 'blue', 'purple'];
colors.splice(2, 2, 'pink', 'orange')
// > [ 'blue', 'purple' ]
console.log(colors)
// > [ 'green', 'yellow', 'pink', 'orange' ]

// 3. Insert elements
let colors = ['green', 'yellow', 'blue', 'purple'];
colors.splice(2, 0, 'red', 'white')
// > []
console.log(colors)
// > [ 'green', 'yellow', 'red', 'white', 'blue', 'purple' ]

// Let's get back to our fruits 🍊🍒🍌
const fruits = [
  { name: "apple", quantity: 3 },
  { name: "orange", quantity: 5 },
  { name: "pear", quantity: 1 },
  { name: "banana", quantity: 0 },
]

// 1. Array.prototype.some() => check if a least one fruit is out of stock
fruits.some(fruit => fruit.quantity === 0)
// > true

// 2. Array.prototype.every() => are every fruits out of stock ?
fruits.every(fruit => fruit.quantity === 0)
// > false

// 3. Array.prototype.includes()
const shoppingList = ['bread', 'milk', 'cofee', 'sugar']
shoppingList.includes('bread')
// > true
shoppingList.includes('orange')
// > false

// Array.sort change the original array, as well a returning 
// its new value (the sorted array)
const numbers = [4, 1, 8, 3, 5]
numbers.sort((a, b) => b - a)
// > [ 8, 5, 4, 3, 1 ]
numbers.sort((a, b) => a - b)
// > [ 1, 3, 4, 5, 8 ]

// If you don't want to mutate the original array, you can spread it before:
const numbers = [4, 1, 8, 3, 5]
const sortedNumbers = [...numbers].sort((a, b) => a - b)
// sortedNumbers = [ 1, 3, 4, 5, 8 ]
// numbers = [4, 1, 8, 3, 5]

const fruits = ['apple', 'orange', 'banana', 'apple', 'kiwi']

// Array.prototype.indexOf()
fruits.indexOf('apple')
// > 0
fruits.indexOf('kiwi')
// > 4
fruits.indexOf('pear')
// > -1

// Array.prototype.lastIndexOf()
fruits.lastIndexOf('apple')
// > 3

// Array.prototype.find()
const numbers = [1, 32, 12, 8, 4, 17]
numbers.find(number => number > 10)
// > [32, 12, 17

// 1. Array.join 
const words = ['Hello', 'wonderful', 'world']
words.join(' ')
// > 'Hello wonderful world'

// 2. Array.split
const sentence = "Hello wonderful world"
sentence.split(' ')
// > [ 'Hello', 'wonderful', 'world' ]

const fruits = [
  { name: "apple", quantity: 3 },
  { name: "orange", quantity: 5 },
  { name: "pear", quantity: 1 },
  { name: "banana", quantity: 0 },
]
fruits
    .sort((fruit1, fruit2) => fruit2.quantity - fruit1.quantity)
    .filter(fruit => fruit.quantity > 0)
    .map(fruit => `${fruit.name} (${fruit.quantity})`)
    .join(', ')
// > 'orange (5), apple (3), pear (1)'

// 1. Make a copy of an array
const arrayCopy = [...originalArray]

// 2. Add elements in the array
const arrayWithNewElements = [newItem, ...originArray, anotherItem] 

// 3. Merge arrays
const mergedArrays = [...array1, ...array2, ...array3]

// 4. Convert a Set into an Array
const arrayFromSet = [...new Set(elements)]

// 5. Populate an empty array
const populatedArray = [...new Array(10)].map((_, idx) => idx)
// > [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]

// 6. Convert an array to an object
const fruits = ['apple', 'orange', 'banana', 'kiwi']
console.log({...fruits})
// > { '0': 'apple', '1': 'orange', '2': 'banana', '3': 'kiwi' }

const array = ['🐑',1,2,'🐑','🐑',3,4];

// OPTION 1 
// Convert to a set and back to an array with the spread operator
const distinct_array = [...new Set(array)];

// OPTION 2 
// Use filter
const distinct_array = array.filter((item, idx) => array.indexOf(item) === idx);

// OPTION 3
// Use reduce
const distinct_array = array.reduce((unique, item) =>
  unique.includes(item) ? unique : [...unique, item]
)

const fruits = ['apple', 'orange', 'banana', 'kiwi']
fruits.length = 0
console.log(fruits)
// > []

const values = [false, 12, 'test', null, true]
values.filter(Boolean)
// > [ 12, 'test', true ]