JavaScript Exercises: Concatenates two stacks into a new stack
JavaScript Stack: Exercise-24 with Solution
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:
See the Pen javascript-stack-exercise-24 by w3resource (@w3resource) on CodePen.
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Stack Previous: Create stacks from arrays.
Stack Exercises Next: Create a copy of the stack.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
JavaScript: Tips of the Day
Creates an array of elements, ungrouping the elements in an array produced by zip and applying the provided function
Example:
const tips_unzip = (arr, fn) => arr .reduce( (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc), Array.from({ length: Math.max(...arr.map(x => x.length)) }).map(x => []) ) .map(val => fn(...val)); console.log(tips_unzip([[2, 15, 200], [3, 25, 300]], (...args) => args.reduce((acc, v) => acc + v, 0)));
Output:
[5, 40, 500]
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