What is JavaScript Program to Reverse a String using Stack?

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JavaScript Program to Reverse a String using Stack

JavaScript Program to Reverse a String Using Recursion

Stack is the LIFO Data Structure that allows reversing a string by pushing characters onto the stack and popping them in reverse order to reconstruct the string.

Below are the approaches to reversing a String using Stack.

Table of Content

Using Array as Stack
Using Custom Stack Implementation

Using Array as Stack

In this approach, we are using an array as a stack to reverse a string.
We iterate through the characters of the string, pushing each character onto the stack.
Then, we pop characters from the stack one by one to construct the reversed string, appending each popped character to the result variable until the stack is empty.

Example: The below example uses Array as a Stack to Reverse a String in JavaScript.

JavaScript

let str = "Hello, GFG!";
let stack = [];
let res = "";
for (let i = 0; i < str.length; i++) {
    stack.push(str[i]);
}
while (stack.length > 0) {
    res += stack.pop();
}
console.log(res);

Output

!GFG ,olleH

Time Complexity: O(n), where n is the length of the input string.

Space Complexity: O(n)

Using Custom Stack Implementation

In this approach, we are using a custom stack implementation using a class.
We define methods like push, pop, and isEmpty to manipulate the stack.
We iterate through the characters of the string, pushing each character onto the stack using the custom push method.
Then, we pop characters from the stack one by one using pop until the stack is empty, constructing the reversed string by appending each popped character to the result variable.

Example: The below example uses Custom Stack Implementation to Reverse a String in JavaScript.

JavaScript

class Stack {
    constructor() {
        this.items = [];
    }
    push(element) {
        this.items.push(element);
    }
    pop() {
        if (this.items.length === 0) {
            return "Underflow";
        }
        return this.items.pop();
    }

    isEmpty() {
        return this.items.length === 0;
    }
}
let str = "Hello, GFG!";
let stack = new Stack();
let res = "";
for (let i = 0; i < str.length; i++) {
    stack.push(str[i]);
}
while (!stack.isEmpty()) {
    res += stack.pop();
}
console.log(res);