JavaScript Exercises: New stack from a portion of the original stack

JavaScript Stack: Exercise-32 with Solution

New Stack from Portion

Write a JavaScript program that implements a stack and creates a new stack from a portion of the original stack.

Sample Solution:

JavaScript Code:

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

  // push element to the stack
  push(element) {
    this.items.push(element);
  }

  // pop element from the stack
  pop() {
    if (this.items.length == 0) {
      return "Underflow";
    }
    return this.items.pop();
  }

  // get the top element of the stack
  peek() {
    return this.items[this.items.length - 1];
  }

  // check if the stack is empty
  isEmpty() {
    return this.items.length == 0;
  }

  // get the size of the stack
  size() {
    return this.items.length;
  }
 fromArray(array) {
    this.items = array.slice(); // copy the array to the items array
  } 
 slice(startIndex, endIndex) {
    const newStack = new Stack();
    const slicedArray = this.items.slice(startIndex, endIndex+1);
    newStack.fromArray(slicedArray);
    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();
 }
}
const stack1 = new Stack();
stack1.push(1);
stack1.push(2);
stack1.push(3);
stack1.push(4);
stack1.push(5);
stack1.push(6);
stack1.push(7);
stack1.push(8);
console.log("Original Stack:");
console.log(stack1.displayStack(stack1));
console.log("Extract a portion from the said stack:");
let index_pos1 = 1;
let index_pos2 = 3;
console.log("Index Position1 = "+index_pos1+" Index Position2 = "+index_pos2);
let result = stack1.slice(index_pos1, index_pos2);
console.log(result.displayStack(result));
index_pos1 = 3;
index_pos2 = 7;
console.log("Index Position1 = "+index_pos1+" Index Position2 = "+index_pos2);
result = stack1.slice(index_pos1, index_pos2);
console.log(result.displayStack(result));

Sample Output:

Original Stack:
Stack elements are:
1 2 3 4 5 6 7 8
Extract a portion from the said stack:
Index Position1 = 1 Index Position2 = 3
Stack elements are:
2 3 4
Index Position1 = 3 Index Position2 = 7
Stack elements are:
4 5 6 7 8

Flowchart:

Live Demo:

See the Pen javascript-stack-exercise-32 by w3resource (@w3resource) on CodePen.

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