Method push

chapter03/3.2 - Stack Min/stackMin.js:13–19

(value)

  }

  push(value) {
    super.push(value);
    if (this._min == null || value <= this._min) {
      this._min = value;
      this._minStack.push(value);
    }
  }

  pop() {
    let value = super.pop();