Code Challenge: 2018-02-01

LinkedList.js

class LinkedList {
    constructor(...values) {
        this.head = null;
        this.length = 0;
        this.add(...values);
    }
    
    /**
     * Individually adds a new node to the head of the linked list.
     * 
     * @param value data to be added.
     */
    _addToHead(value) {
        const newNode = {
            value,
            next: this.head
        };

        this.head = newNode;
        this.length++;
    }

    /**
     * Adds to the head, in sequential order, an indefinite number of arguements.
     * 
     * @param values data values to be individually added.
     * @returns the full linked list.
     */
    add(...values) {
        values.forEach(value => this._addToHead(value));

        return this;
    }
    
    /**
     * Removes from the linked list the node at the head.
     * 
     * @returns the data from the node removed.
     */
    _removeFromHead() {
        if (this.length === 0) {
            return undefined;
        }
        
        const value = this.head.value;

        this.head = this.head.next;
        this.length--;
        
        return value;
    }
    
    /**
     * Removes a single node from the linked list with the value provided.
     * 
     * @todo accept an indefinite number of values.
     * 
     * @param value the data of the node to be removed.
     * @returns undefined if not found; the data if at the head; or the full linked list. 
     */
    remove(value) {
        if(this.length === 0) {
            return undefined;
        }
        
        if (this.head.value === value) {
            return this._removeFromHead();
        }
        
        let previousNode = this.head;
        let thisNode = previousNode.next;
        
        while(thisNode) {
            if(thisNode.value === value) {
                break;
            }
            
            previousNode = thisNode;
            thisNode = thisNode.next;
        }
        
        if (thisNode === null) {
            return undefined;
        }
        
        previousNode.next = thisNode.next;
        this.length--;

        return this;
    }

    /**
     * Finds the node with the specific value provided.
     * 
     * @param value the data of the node to be found.
     * @returns the node where data was found.
     */
    find(value) {
        let thisNode = this.head;
        
        while(thisNode) {
            if(thisNode.value === value) {
                return thisNode;
            }
            
            thisNode = thisNode.next;
        }
        
        return thisNode;
    }
}

const myList = new LinkedList();
console.log('Adding values 4, 7 and 8 to the head:\n', JSON.stringify(myList.add(4, 7, 8), null, '\t'));
console.log('Finding node with value 7:\n', JSON.stringify(myList.find(7), null, '\t'));
console.log('Removing node with value 7:\n', JSON.stringify(myList.remove(7), null, '\t'));