froebel/surround.mjs

TypeScript utility library

import { assert } from "./except.mjs";
/**
 * Surrounds the `str` with `surrounding`. `surrounding` must have an even length.
 *
 * @example
 * ```
 * surround("foo", "()")      // "(foo)"
 * surround("foo", "({[]})")  // "({[foo]})"
 * ```
 */

export const surround = (str, surrounding) => {
  if (typeof surrounding !== "string") return str;
  assert(surrounding.length % 2 === 0, "surrounding string must have even length");
  const half = surrounding.length / 2;
  return `${surrounding.slice(0, half)}${str}${surrounding.slice(half, half * 2)}`;
};
export default surround;