array.map(callback)
let arr = [1, 2, 3]
arr.map(item => item + 1) // [2, 3, 4]
array.forEach(callback)
let arr = [1, 2, 3]
arr.forEach(item => {
item > 2 && console.log(item); // 3
})
array.find(callback)
let arr = [1, 2, 3]
arr.find(item => item > 2) // 3
array.filter(callback)
let arr = [1, 2, 3]
arr.filter(item => item > 2) // [3]
array.reduce(callback, init)
let arr = [1, 2, 3]
let num = arr.reduce((total, num) => {
return total + num
}, 0)
console.log(num); // 6
