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

title

title
Create a Stack Class

Create a Stack Class

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Problem Explanation

• 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

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Solutions

Solution 1 (Click to Show/Hide)

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;
  };
}

Solution 2 (Click to Show/Hide)

class Stack {
  constructor() {
    this.collection = [];
  }
  print() {
    console.log(this.collection);
  }
  push(val) {
    return 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);
  }
}

Relevant Links

• Wikipedia