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Data Structures in TypeScript - Stack

Ricardo Borges
Originally published at ricardoborges.dev Updated on ・1 min read

A stack uses LIFO (last-in-first-out) ordering, the most recent item added is the first item to be removed, just like a real stack.
Some uses of this data structure are expressions evaluations and conversion (prefix, postfix, and infix), backtracking, and memory management.

stack

Representation

A stack can be implemented using an array or a linked list, can be either fixed or dynamic size.

Basic operations

  • Push - Add an item to the top of the stack
  • Pop - Remove the top item from the stack
  • Peek - Return the top of the stack, without removing it.
  • isEmpty - Return true if the stack is empty.
  • isFull - Return true if the stack is full, used when the stack is fixed size.

Here's an implementation of a stack using an array, in TypeScript an array doesn't have a fixed length, so the operation isFull is not required, however you can implement a stack with a fixed length and use that operation.

class Stack<T> {
  private array: T[] = [];

  pop(): T | undefined {
    if (this.isEmpty()) throw new EmptyStackException();

    return this.array.pop();
  }

  push(data: T): void {
    this.array.push(data);
  }

  peek(): T {
    if (this.isEmpty()) throw new EmptyStackException();

    return this.array[this.array.length - 1];
  }

  isEmpty(): boolean {
    return this.array.length === 0;
  }
}
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