Method peekBack

data_structures/deque.ts:455–458

* Return the back element without removing it, or `undefined` if the deque * is empty. * * @example Peeking at the back * ```ts * import { Deque } from "@std/data-structures/deque"; * import { assertEquals } from "@std/assert"; * * const deque = new Deque([1, 2, 3]); * ass

()

   * @returns The back element, or `undefined` if empty.
   */
  peekBack(): T | undefined {
    if (this.#length === 0) return undefined;
    return this.#buffer[(this.#head + this.#length - 1) & this.#mask];
  }

  /**
   * Return the element at the given index (0-based from front). Negative