difference

Returns values from the first array that do not occur in the comparison arrays.

Code

difference.ts

/** Returns values from the first array that are absent from every other array. */
export const difference = <const T>(
  array: readonly T[],
  ...others: ReadonlyArray<readonly unknown[]>
): T[] => {
  const excluded = new Set<unknown>();
  for (const other of others) {
    if (!Array.isArray(other)) {
      throw new TypeError("comparison values must be arrays");
    }
    for (let index = 0; index < other.length; index += 1) {
      if (Object.hasOwn(other, index)) excluded.add(other[index]);
    }
  }
  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 (!excluded.has(value)) result.push(value);
  }
  return result;
};

Download

wget

Terminal

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

degit

Terminal

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

Examples

difference.example.ts

import { difference } from "./difference";

const available = difference(["read", "write", "delete"], ["delete"]);
// ["read", "write"]

Props

• array (readonly T[]) — Values to filter. Empty slots are skipped.
• ...others (readonly (readonly unknown[])[]) — Arrays containing excluded values. Empty slots are skipped, not treated as undefined, and their element types do not widen the result.
• Returns a new T[] and preserves duplicates from the first array.