node js javascript stack implementation example data structure

stack.js

console.time('stack');

const assert = require('assert'); // for tests

class Stack {
  constructor() {
    this.list = []
  }
  isEmpty() {
    return !this.list.length;
  }
  clear() {
    this.list = [];
    return this.list;
  }
  peek() {
    if (this.isEmpty()) {
      return null;
    }

    return this.list[0];
  }
  push(value) {
    return this.list.unshift(value);
  }
  pop() {
    return this.list.pop();
  }
  toArray() {
    return [...this.list];
  }
  toString() {
    return this.list.toString();
  }
}

const stack = new Stack();
console.log('%O', stack);


assert.equal(stack.peek(), null);

assert.equal(stack.push(1), 1);
assert.equal(stack.push(2), 2);
assert.deepEqual(stack.toArray(), [2,1]);

assert.equal(stack.toString(), '2,1');

assert.equal(stack.peek(), 2);
assert.equal(stack.peek(), 2);
assert.equal(stack.isEmpty(), false);

assert.equal(stack.pop(), 1);
assert.equal(stack.pop(), 2);
assert.equal(stack.pop(), null);
assert.equal(stack.isEmpty(), true);

assert.deepEqual(stack.clear(), []);
assert.deepEqual(stack.toArray(), []);

console.timeEnd('stack');

// node stack.js