Array.prototype.entries()

entries()

Returns: Iterator · Updated March 13, 2026 · Array Methods

array entries iteration

The entries() method returns a new array iterator that contains the key-value pairs for each index in the array. This allows you to iterate over both the index and the value of each element in a single pass.

Syntax

array.entries()

Parameters

None. This method takes no parameters.

Examples

Basic usage with iterator

const fruits = ['apple', 'banana', 'cherry'];
const iterator = fruits.entries();

console.log(iterator.next().value);
// [0, 'apple']

console.log(iterator.next().value);
// [1, 'banana']

console.log(iterator.next().value);
// [2, 'cherry']

Using for…of loop

const colors = ['red', 'green', 'blue'];

for (const [index, value] of colors.entries()) {
  console.log(`Index ${index}: ${value}`);
}
// Index 0: red
// Index 1: green
// Index 2: blue

Converting to an array of pairs

const nums = [10, 20, 30];
const pairs = [...nums.entries()];
console.log(pairs);
// [[0, 10], [1, 20], [2, 30]]

Finding index with value condition

const data = [5, 12, 8, 130, 44];

for (const [index, value] of data.entries()) {
  if (value > 100) {
    console.log(`Found ${value} at index ${index}`);
    break;
  }
}
// Found 130 at index 3

Filtering by index

const items = ['a', 'b', 'c', 'd', 'e'];

// Get items at odd indices
const oddItems = [...items.entries()]
  .filter(([index]) => index % 2 === 1)
  .map(([, value]) => value);

console.log(oddItems); // ['b', 'd']

Transforming with index awareness

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

// Multiply each number by its index
const indexed = [...numbers.entries()].map(([i, n]) => n * i);
console.log(indexed); // [0, 2, 6, 12, 20]

Practical: finding duplicate indices

const arr = [1, 2, 3, 2, 4, 3, 5];
const seen = new Set();

for (const [index, value] of arr.entries()) {
  if (seen.has(value)) {
    console.log(`Duplicate ${value} at index ${index}`);
  } else {
    seen.add(value);
  }
}
// Duplicate 2 at index 3
// Duplicate 3 at index 5

Object creation from entries

const keys = ['name', 'age', 'city'];
const values = ['Alice', 30, 'NYC'];

const obj = Object.fromEntries(keys.entries().map(([i, k], _, arr) => 
  [k, values[i]]
));
console.log(obj); // { name: 'Alice', age: 30, city: 'NYC' }

Notes

The returned iterator yields [index, value] pairs
Destructuring in for...of (const [index, value]) is the cleanest pattern
Iterator can be converted to array with spread operator