JavaScript Exercises: Remove elements from a stack that do not meet a condition

JavaScript Stack: Exercise-35 with Solution

Filter Stack by Condition

Write a JavaScript program that implements a stack and create a new stack by removing elements that do not satisfy a condition.

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;
  }

  filter(callback) {
    let result_stack = new Stack();
    for (let i = 0; i < this.items.length; i++) {
      if (callback(this.items[i])) {
        result_stack.push(this.items[i]);
      }
    }
    return result_stack;
  }
  
 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("Create new stack, values greater than 5:");
let result = stack1.filter((element) => element > 5);
console.log(result.displayStack(result));
console.log("Create new stack, values less than 5:");
result = stack1.filter((element) => element < 5);
console.log(result.displayStack(result));
console.log("Create new stack, only even numbers:");
result = stack1.filter((element) => element % 2 === 0);
console.log(result.displayStack(result));
console.log("Create new stack, only odd numbers:");
result = stack1.filter((element) => element % 2 !== 0);
console.log(result.displayStack(result));

Sample Output:

Original Stack:
Stack elements are:
1 2 3 4 5 6 7 8
Create new stack, values greater than 5:
Stack elements are:
6 7 8
Create new stack, values less than 5:
Stack elements are:
1 2 3 4
Create new stack, only even numbers:
Stack elements are:
2 4 6 8
Create new stack, only odd numbers:
Stack elements are:
1 3 5 7

Flowchart:

Live Demo:

See the Pen javascript-stack-exercise-35 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that filters a stack based on a provided predicate and returns a new stack with only the elements that satisfy the condition.
• Write a JavaScript function that iterates over a stack and removes elements that do not meet the criteria, preserving the order of remaining items.
• Write a JavaScript function that converts a stack to an array, applies the filter() method, and then reconstructs a stack from the filtered array.
• Write a JavaScript function that validates the condition function and ensures the original stack remains unmodified while creating the filtered stack.

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