codecademydev/LinkedList.js Secret

## index.js
const Node = require("./Node");
const LinkedList = require("./LinkedList");

const myList = new LinkedList();

myList.addToHead("Node 1");
myList.addToHead("Node 2");
myList.addToHead("Node 3");
myList.addToHead("Node 4");

// Add checkpoint 2 code below:
const myNodeRecursive = myList.findNodeIteratively("Node 2");
console.log(myNodeRecursive);

## LinkedList.js
const Node = require("./Node");

class LinkedList {
  constructor() {
    this.head = null;
  }

  addToHead(data) {
    const nextNode = new Node(data);
    const currentHead = this.head;
    this.head = nextNode;
    if (currentHead) {
      this.head.setNextNode(currentHead);
    }
  }

  addToTail(data) {
    let lastNode = this.head;
    if (!lastNode) {
      this.head = new Node(data);
    } else {
      let temp = this.head;
      while (temp.getNextNode() !== null) {
        temp = temp.getNextNode();
      }
      temp.setNextNode(new Node(data));
    }
  }

  removeHead() {
    const removedHead = this.head;
    if (!removedHead) {
      return;
    }
    if (removedHead.next) {
      this.head = removedHead.next;
    }
    return removedHead.data;
  }

  printList() {
    let currentNode = this.head;
    let output = "<head> ";
    while (currentNode !== null) {
      output += currentNode.data + " ";
      currentNode = currentNode.next;
    }
    output = output.concat("<tail>");
    console.log(output);
  }

  findNodeIteratively(data) {
    let currentNode = this.head;
    while (currentNode !== null) {
      if (currentNode.data === data) {
        return currentNode;
      }
      currentNode = currentNode.next;
    }
    return null;
  }

  findNodeRecursively(data, currentNode = this.head) {
    if (currentNode === null) {
      return null;
    } else if (currentNode.data === data) {
      return currentNode;
    } else {
      return this.findNodeRecursively(data, currentNode.next);
    }
  }
}

module.exports = LinkedList;

## Node.js
class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }

  setNextNode(node) {
    if (!(node instanceof Node)) {
      throw new Error("Next node must be a member of the Node class");
    }
    this.next = node;
  }

  setNext(data) {
    this.next = data;
  }

  getNextNode() {
    return this.next;
  }
}

module.exports = Node;
	const Node = require("./Node");
	const LinkedList = require("./LinkedList");

	const myList = new LinkedList();

	myList.addToHead("Node 1");
	myList.addToHead("Node 2");
	myList.addToHead("Node 3");
	myList.addToHead("Node 4");

	// Add checkpoint 2 code below:
	const myNodeRecursive = myList.findNodeIteratively("Node 2");
	console.log(myNodeRecursive);
	const Node = require("./Node");

	class LinkedList {
	constructor() {
	this.head = null;
	}

	addToHead(data) {
	const nextNode = new Node(data);
	const currentHead = this.head;
	this.head = nextNode;
	if (currentHead) {
	this.head.setNextNode(currentHead);
	}
	}

	addToTail(data) {
	let lastNode = this.head;
	if (!lastNode) {
	this.head = new Node(data);
	} else {
	let temp = this.head;
	while (temp.getNextNode() !== null) {
	temp = temp.getNextNode();
	}
	temp.setNextNode(new Node(data));
	}
	}

	removeHead() {
	const removedHead = this.head;
	if (!removedHead) {
	return;
	}
	if (removedHead.next) {
	this.head = removedHead.next;
	}
	return removedHead.data;
	}

	printList() {
	let currentNode = this.head;
	let output = "<head> ";
	while (currentNode !== null) {
	output += currentNode.data + " ";
	currentNode = currentNode.next;
	}
	output = output.concat("<tail>");
	console.log(output);
	}

	findNodeIteratively(data) {
	let currentNode = this.head;
	while (currentNode !== null) {
	if (currentNode.data === data) {
	return currentNode;
	}
	currentNode = currentNode.next;
	}
	return null;
	}

	findNodeRecursively(data, currentNode = this.head) {
	if (currentNode === null) {
	return null;
	} else if (currentNode.data === data) {
	return currentNode;
	} else {
	return this.findNodeRecursively(data, currentNode.next);
	}
	}
	}

	module.exports = LinkedList;
	class Node {
	constructor(data) {
	this.data = data;
	this.next = null;
	}

	setNextNode(node) {
	if (!(node instanceof Node)) {
	throw new Error("Next node must be a member of the Node class");
	}
	this.next = node;
	}

	setNext(data) {
	this.next = data;
	}

	getNextNode() {
	return this.next;
	}
	}

	module.exports = Node;