sampleSize()

sampleSize<T>(array, n): T[]

Gets n random elements from an array.

note

Uses Fisher-Yates shuffle algorithm for unbiased sampling.

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Type Parameters

T: T

The type of elements in the array.

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Parameters

array: readonly T[]

The array to sample from.

n: number

The number of elements to sample.

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Returns: T[]

A new array of sampled elements.

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Throws

RangeError If n is negative.

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Since

2.0.0

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Performance

O(n) time & space for the shuffled copy.

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Also known as

sample (Remeda) · sampleSize (Lodash, es-toolkit) · ❌ (Radashi, Ramda, Effect, Modern Dash, Antfu)

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Example

sampleSize([1, 2, 3, 4, 5], 3);
// => [3, 1, 5] (random)

sampleSize(['a', 'b', 'c'], 2);
// => ['b', 'a'] (random)

sampleSize([1, 2, 3], 5);
// => [2, 3, 1] (returns all if n > length)

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How it works?

Returns n random elements using partial Fisher-Yates shuffle.

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Use Cases

Select multiple random items for testing 📌

Get N random elements from an array for sampling or testing. Perfect for generating test data, random selections, or batch sampling.

#random#multiple#sampling#testing#selection

const products = [
  { id: 1, name: "Laptop" },
  { id: 2, name: "Phone" },
  { id: 3, name: "Tablet" },
  { id: 4, name: "Watch" },
  { id: 5, name: "Headphones" },
];

const testSample = sampleSize(products, 3);
// => [{ id: 3, name: "Tablet" }, { id: 1, name: "Laptop" }, { id: 5, name: "Headphones" }]

Generate random playlist

Select random tracks for a shuffled playlist. Ideal for music apps, content recommendations, or quiz questions.

#playlist#random#shuffle#music#tracks

const allSongs = ["Song A", "Song B", "Song C", "Song D", "Song E", "Song F"];

const playlist = sampleSize(allSongs, 4);
// => ["Song C", "Song A", "Song F", "Song D"]

Random survey participants

Select a random subset of users for surveys or feedback. Useful for user research, A/B testing, or focus groups.

#survey#participants#random subset#user research#A/B testing

const allUsers = [
  { id: "u1", name: "Alice" },
  { id: "u2", name: "Bob" },
  { id: "u3", name: "Charlie" },
  { id: "u4", name: "Diana" },
  { id: "u5", name: "Eve" },
];

const surveyGroup = sampleSize(allUsers, 2);
// => [{ id: "u3", name: "Charlie" }, { id: "u1", name: "Alice" }]