unique

Removes duplicate values while preserving their first-seen order.

Code

unique.ts

/** Removes duplicate values while preserving their first-seen order. */
export const unique = <const T>(array: readonly T[]): T[] => {
  const seen = new Set<T>();
  const result: T[] = [];
  for (let index = 0; index < array.length; index += 1) {
    if (!Object.hasOwn(array, index)) continue;
    const value = array[index] as T;
    if (seen.has(value)) continue;
    seen.add(value);
    result.push(value);
  }
  return result;
};

Download

wget

Terminal

wget -O src/lib/unique.ts https://raw.githubusercontent.com/jrTilak/lazykit/HEAD/registry/functions/unique.ts

degit

Terminal

temp_dir="$(mktemp -d)" && bunx degit jrTilak/lazykit/registry/functions "$temp_dir" && mv "$temp_dir/unique.ts" src/lib/unique.ts && rm -r "$temp_dir"

Examples

unique.example.ts

import { unique } from "./unique";

const arr = [1, 2, 3, 3];
const result = unique(arr);
console.log(result);
// Expected Output: [1, 2, 3]

Props

• array (readonly T[]) — Values to deduplicate using Set equality semantics. Empty slots are skipped.

Returns

T[] — A new array containing the first occurrence of each value.