JavaScript Exercises: Concatenates two stacks into a new stack

Last update on March 04 2025 09:36:06 (UTC/GMT +8 hours)

JavaScript Stack: Exercise-24 with Solution

Stack Concat Operation

Write a JavaScript program to implement a stack that supports concat() operation, which concatenates two stacks into a new stack.

Sample Solution:

JavaScript Code:

class Stack {
  constructor() {
    this.items = [];
  }

  push(element) {
    this.items.push(element);
  }

  pop() {
    if (this.isEmpty()) {
      return "Underflow";
    }
    return this.items.pop();
  }
  peek() {
    if (this.isEmpty()) {
      return "No elements in Stack";
    }
    return this.items[this.items.length - 1];
  }
  isEmpty() {
    return this.items.length == 0;
  }
  size() {
    return this.items.length;
  }
  concat(stack) {
    let newStack = new Stack();
    let arr = this.items.concat(stack.items);
    for (let i = 0; i < arr.length; i++) {
      newStack.push(arr[i]);
    }
    return newStack;
  }
  displayStack(stack) {
  console.log("Stack elements are:");
  let str = "";
  for (let i = 0; i < stack.items.length; i++)
    str += stack.items[i] + " ";
  return str.trim();
 } 
}
let stack1 = new Stack();
stack1.push(10);
stack1.push(20);
stack1.push(30);
console.log("Stack1:");
console.log(stack1.displayStack(stack1));
let stack2 = new Stack();
stack2.push(40);
stack2.push(50);
stack2.push(60);
stack2.push(70);
console.log("Stack2:");
console.log(stack2.displayStack(stack2));
let stack3 = stack1.concat(stack2);
console.log("Concatenates of said two stacks into a new stack:");
console.log(stack3.displayStack(stack3));

Sample Output:

Stack1:
Stack elements are:
10 20 30
Stack2:
Stack elements are:
40 50 60 70
Concatenates of said two stacks into a new stack:
Stack elements are:
10 20 30 40 50 60 70

Flowchart:

Live Demo:

For more Practice: Solve these Related Problems:

Write a JavaScript function that concatenates two stacks into a new stack while preserving the order of elements from each.
Write a JavaScript function that uses array concatenation to merge two stacks and returns the resulting stack.
Write a JavaScript function that combines two stacks using recursion and then verifies that the new stack contains all elements.
Write a JavaScript function that handles duplicate elements during concatenation by eliminating repeated values.

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Stack Previous: Create stacks from arrays.
Stack Exercises Next: Create a copy of the stack.