SOURCE

let arr = [11, 22, 33, 44, 55]
arr.forEach((item, index, arr) => {
    console.log(item)
    console.log(arr)
})
for (let k in arr) {
    console.log(k)
}
for (let item of arr) {
    console.log(item)
}

console.log(arr.indexOf(22))
console.log(arr.concat([66, 77]))

console.log(arr.find((item, index, arr) => {
    console.log(arr)
    return item == 44
}))
console.log(arr.findIndex((item, index, arr) => {
    return item == 11
}))
console.log(arr.filter((item, index, arr) => {
    console.log(arr)
    return index < 4
}))
console.log(arr.map((item, index, arr) => {
    console.log(arr)
    item *= 2
    return ++item
}))

let arrr = [1, 5, 3, 4]
arrr.sort((a, b) => b - a)
console.log(arrr)

let ar = [1, 2, 3, 4, 5]

let result = ar.reduce((sum, current) => {
    return sum + current
}, 100)
console.log(result)

console.log(Array.isArray(ar))