singlyLinkedList.js

/* The above class defines a singly linked list data structure in JavaScript with methods for basic
operations like prepend, append, insert, remove, search, reverse, clear, and print. */
class Node {
  constructor(data) {
    this.data = data;
    this.next = null;
  }
}

export class SinglyLinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.size = 0;
  }

  // isEmpty
  isEmpty() {
    return this.size === 0;
  }
  // get size
  getSize() {
    return this.size;
  }
  // prepend
  prepend(data) {
    const node = new Node(data);
    if (this.isEmpty()) {
      this.head = node;
      this.tail = node;
    } else {
      node.next = this.head;
      this.head = node;
    }
    this.size++;
  }
  // append
  append(data) {
    if (this.isEmpty()) {
      return this.prepend(data);
    }
    const node = new Node(data);
    this.tail.next = node;
    this.tail = node;
    this.size++;
  }
  //   remove from head
  removeHead() {
    if (this.isEmpty()) {
      return null;
    } else {
      const removedNode = this.head;
      this.head = this.head.next;
      this.size--;
      return removedNode.data;
    }
  }
  // remove from tail
  removeTail() {
    if (this.isEmpty()) {
      return null;
    }
    const removedNode = this.tail;
    if (this.size === 1) {
      this.head = null;
      this.tail = null;
    } else {
      this.tail = this.tail.next;
      this.size--;
      return removedNode.data;
    }
  }
  // insert
  insert(data, index) {
    if (index < 0 || index >= this.size) {
      return console.log("Index out of bounds");
    }

    if (index === 0) {
      return this.prepend(data);
    }

    const node = new Node(data);
    let current = this.head;
    let previous;
    let count = 0;
    while (count < index) {
      previous = current;
      current = current.next;
      count++;
    }
    node.next = current;
    previous.next = node;
    this.size++;
  }
  // get index
  getIndex(index) {
    if (index < 0 || index >= this.size) {
      return console.log("Index out of bounds");
    }

    let current = this.head;
    let count = 0;
    while (count < index) {
      current = current.next;
      count++;
    }
    return console.log("data at index " + index + ": ", current.data);
  }
  // search
  search(data) {
    if (this.isEmpty()) {
      return console.log("List is empty");
    }
    let current = this.head;
    let index = 0;
    while (current) {
      if (current.data === data) {
        return console.log("data found at index: ", index);
      }
      current = current.next;
      index++;
    }
    return console.log("data not found in the list");
  }
  // remove by index
  removeIndex(index) {
    if (index < 0 || index >= this.size) {
      return console.log("Index out of bounds");
    }
    if (index === 0) {
      const removedNode = this.head;
      this.head = this.head.next;
      this.size--;
      return console.log("Removed data: ", removedNode.data);
    }
    let current = this.head;
    let previous;
    let count = 0;
    while (count < index) {
      previous = current;
      current = current.next;
      count++;
    }
    previous.next = current.next;
    this.size--;
    return console.log("Removed data: ", current.data);
  }
  // remove by data
  removeData(data) {
    if (this.isEmpty()) {
      return console.log("List is empty");
    }
    let current = this.head;
    let previous;
    while (current) {
      if (current.data === data) {
        if (current === this.head) {
          this.head = this.head.next;
        } else {
          previous.next = current.next;
        }
        this.size--;
        return console.log("Removed data: ", current.data);
      }
      previous = current;
      current = current.next;
    }
  }
  // reverse
  reverse() {
    if (this.isEmpty()) {
      return console.log("List is empty");
    }
    let current = this.head;
    let previous = null;
    let next;
    while (current) {
      next = current.next;
      current.next = previous;
      previous = current;
      current = next;
    }
    this.head = previous;
  }
  // clear
  clear() {
    this.head = null;
    this.tail = null;
    this.size = 0;
  }
  // print
  print() {
    if (this.isEmpty()) {
      console.log("List is empty");
    }
    let current = this.head;
    while (current) {
      console.log(current.data);
      current = current.next;
    }
  }
}

// const list = new SinglyLinkedList();
// console.log("List is empty: ", list.isEmpty());
// console.log("List size: ", list.getSize());
// list.prepend(10);
// list.prepend(20);
// list.append(5);
// list.append(15);
// list.print();
// console.log("------------------------------");
// list.insert(22, 2);
// list.getIndex(3);
// list.search(5);
// console.log("------------------------------");
// list.print();
// list.removeHead(2);
// list.removeTail(15);
// list.print();
// list.reverse();
// list.print();
// list.clear();
// console.log("List is empty: ", list.isEmpty());
// console.log("List size: ", list.getSize());