Arrays

Arrays are ordered lists of values. They can contain any type of data.

Creating Arrays

const fruits = ['apple', 'banana', 'cherry']
const mixed = [1, 'hello', true, null, { x: 1 }]
const empty = []

Accessing Elements

fruits[0]          // 'apple' (zero-indexed)
fruits[fruits.length - 1]  // 'cherry' (last element)
fruits.at(-1)      // 'cherry' (ES2022)

Modifying Arrays

fruits.push('date')      // add to end
fruits.pop()             // remove from end
fruits.unshift('avocado')// add to beginning
fruits.shift()           // remove from beginning
fruits.splice(1, 1)      // remove 1 element at index 1

Useful Methods

const nums = [3, 1, 4, 1, 5, 9, 2, 6]

nums.length             // 8
nums.includes(5)        // true
nums.indexOf(1)         // 1 (first occurrence)
nums.sort()             // [1, 1, 2, 3, 4, 5, 6, 9]
nums.reverse()          // [9, 6, 5, 4, 3, 2, 1, 1]
nums.join(', ')         // '9, 6, 5, 4, 3, 2, 1, 1'
nums.slice(0, 3)        // [9, 6, 5] (non-destructive)

for...of with Arrays

for (const fruit of fruits) {
  console.log(fruit)
}