15 JavaScript array methods

arrayMethods.js

// .some()
const myAwesomeArray = ["a", "b", "c", "d", "e"]
myAwesomeArray.some(test => test === "d") // true

// .reduce()
const myAwesomeArray = [1, 2, 3, 4, 5]
myAwesomeArray.reduce((total, value) => total * value) // 1*2*3*4*5 = 120

// .every()
const myAwesomeArray = ["a", "b", "c", "d", "e"]
myAwesomeArray.every(test => test === "d") // false
const myAwesomeArray2 = ["a", "a", "a", "a", "a"]
myAwesomeArray2.every(test => test === "a") // true

// .map()
const myAwesomeArray = [5, 4, 3, 2, 1]
myAwesomeArray.map(x => x * x) // [25, 16, 9, 4, 1]

// .flat()
const myAwesomeArray = [[1, 2], [3, 4], 5]
myAwesomeArray.flat() // [1, 2, 3, 4, 5] 

// .filter()
const myAwesomeArray = [{ id: 1, name: "john" }, { id: 2, name: "Mass" }, { id: 3, name: "Mass" }]
myAwesomeArray.filter(element => element.name === "Mass") // [{ id: 2...}, { id: 3...}]

// .forEach()
const myAwesomeArray = [{ id: 1, name: "john" }, { id: 2, name: "Ali" }, { id: 3, name: "Mass" }]
myAwesomeArray.forEach(element => console.log(element.name)) // John, Ali, Mass

// .findIndex()
const myAwesomeArray = [{ id: 1, name: "john" }, { id: 2, name: "Ali" }, { id: 3, name: "Mass" }]
myAwesomeArray.findIndex(element => element.id === 3) // 2
myAwesomeArray.findIndex(element => element.id === 7) // -1

// .find()
const myAwesomeArray = [{ id: 1, name: "john" }, { id: 2, name: "Ali" }, { id: 3, name: "Mass" }]
myAwesomeArray.find(element => element.id === 3) // {id: 3, name: "Mass"}
myAwesomeArray.find(element => element.id === 7) // undefined

// .sort()
const myAwesomeArray = [5, 4, 3, 2, 1]
myAwesomeArray.sort((a, b) => a - b) // [1, 2, 3, 4, 5]
myAwesomeArray.sort((a, b) => b - a) // [5, 4, 3, 2, 1]

// .concat()
const myAwesomeArray = [1, 2, 3, 4, 5]
const myAwesomeArray2 = [10, 20, 30, 40, 50]
myAwesomeArray.concat(myAwesomeArray2) // [1, 2, 3, 4, 5, 10, 20, 30, 40, 50]

// .fill(value, start, end)
const myAwesomeArray = [1, 2, 3, 4, 5]
myAwesomeArray.fill(0, 1, 3) // [1, 0, 0, 4, 5]

// .includes()
const myAwesomeArray = [1, 2, 3, 4, 5]
myAwesomeArray.includes(3) // true
myAwesomeArray.includes(8) // false

// .reverse()
const myAwesomeArray = ["e", "d", "c", "b", "a"]
myAwesomeArray.reverse() // ['a', 'b', 'c', 'd', 'e']

// .flatMap()
const myAwesomeArray = [[1], [2], [3], [4], [5]]
myAwesomeArray.flatMap(arr => arr * 10) // [10, 20, 30, 40, 50]
myAwesomeArray.flat().map(arr => arr * 10) // [10, 20, 30, 40, 50]