freeCodeCamp Challenge Guide: Create a Stack Class

Guide
1

Create a Stack Class

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.
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Stack n n 1 1

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);
  }
}

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