freeCodeCamp/guide/english/certifications/coding-interview-prep/data-structures/create-a-stack-class/index.md

title
Create a Stack Class

Create a Stack Class

Method:

• Stack is an abstract data structure.
• Stack follows LIFO/FILO principle.
• In this challenge, we need to add .push(), .pop(), .peek(), .isEmpty() and .clear() methods to the class.
• push() method pushes value to the stack.
• pop() method pops the first value from the stack.
• peek() method returns the first value from the stack.
• isEmpty() method checks if ths stack is empty.
• .clear() method removes all the elements from the stack.

DS	Access	Search	Insert	Delete
Stack	n	n	1	1

Solution:

Basic:

function Stack() { 
    var collection = [];
    this.print = function() {
        console.log(collection);
    };
    this.push = function(val){
        return collection.push(val);
    }
    this.pop = function(){
        return collection.pop();
    }
    this.peek = function(){
        return collection[collection.length-1];
    }
    this.isEmpty = function(){
        return collection.length === 0;
    }
    this.clear = function(){
        collection.length = 0;
    }
}

Advanced - ES6 Class syntax:

class Stack {
    constructor() {
        this.collection = [];
    }
    print(){
        console.log(this.collection);
    }
    push(val){
        retiurn this.collection.push(val);
    }
    pop(){
        return this.collection.pop();
    }
    peek(){
        return this.collection[this.collection.length-1];
    }
    isEmpty(){
        return this.collection.length === 0;
    }
    clear(){
        return this.collection.length = 0;
    }
}

Resources:

• Wikipedia