singly-linked-list.js

// Singly Linked List data structure implementation 
// in javascript. (not all methods)

class SinglyListNode {
	constructor(data) {
		this.data = data;
		this.next = null;
	}
}

class SinglyLinkedList {
	constructor() {
		this.head = null;
		this.tail = null;

		this.length = 0;
	}

	addLast(value) {
		const node = new SinglyListNode(value);

		if (this.length == 0) {
			this.head = node;
		} else {
			this.tail.next = node;
		}

		this.tail = node;
		this.length++;

		return this;
	}

	addFirst(value) {
		const node = new SinglyListNode(value);
		const temp = this.head;

		this.head = node;
		this.head.next = temp;

		if (this.length === 1) this.tail = temp;

		this.length++;

		return this;
	}

	removeFirst() {
		if (this.length !== 0) {
			if (this.length === 1) {
				this.head = null;
				this.tail = null;
			} else {
				this.head = this.head.next;
			}

			this.length--;
		}

		return this;
	}

	removeLast() {
		if (this.length !== 0) {
			if (this.length === 1) {
				this.head = null;
				this.tail = null;
			} else {
				let current = this.head;

				while (current.next !== this.tail) {
					current = current.next;
				}

				current.next = null;
				this.tail = current;
			}

			this.length--;
		}

		return this;
	}

	clear() {
		this.head = null;
		this.tail = null;

		this.length = 0;

		return this;
	}
}