Modern JavaScript Array Methods You Should Know

Modern JavaScript provides powerful array methods. Let’s explore the essential ones.

Array.prototype.at()

javascript

const arr = [1, 2, 3, 4, 5]

arr.at(0)   // 1
arr.at(-1)  // 5 (last element)
arr.at(-2)  // 4

Array.prototype.findLast()

javascript

const numbers = [1, 2, 3, 4, 5, 4, 3]

numbers.findLast(n => n > 3)      // 4
numbers.findLastIndex(n => n > 3) // 5

Array.prototype.toSorted()

Non-mutating sort:

javascript

const original = [3, 1, 4, 1, 5]
const sorted = original.toSorted()

console.log(original) // [3, 1, 4, 1, 5]
console.log(sorted)   // [1, 1, 3, 4, 5]

Array.prototype.toReversed()

javascript

const arr = [1, 2, 3]
const reversed = arr.toReversed()

console.log(arr)      // [1, 2, 3]
console.log(reversed) // [3, 2, 1]

Array.prototype.toSpliced()

javascript

const arr = [1, 2, 3, 4, 5]
const newArr = arr.toSpliced(1, 2, 'a', 'b')

console.log(arr)    // [1, 2, 3, 4, 5]
console.log(newArr) // [1, 'a', 'b', 4, 5]

Array.prototype.with()

javascript

const arr = [1, 2, 3]
const newArr = arr.with(1, 'two')

console.log(arr)    // [1, 2, 3]
console.log(newArr) // [1, 'two', 3]

Practical Examples

javascript

// Chain methods for powerful transformations
const users = [
  { name: 'Alice', age: 30 },
  { name: 'Bob', age: 25 },
  { name: 'Charlie', age: 35 }
]

const result = users
  .filter(u => u.age >= 25)
  .toSorted((a, b) => a.age - b.age)
  .map(u => u.name)

// ['Bob', 'Alice', 'Charlie']