Defined and declared class MerkleTree with constructor

src/data-structures/tree/merkle-tree/MerkleTree.js

@@ -0,0 +1,49 @@
+var crypto = require('crypto');
+
+class MerkleTree {
+    /**
+     * @desc Constructs a Merkle Tree.
+     * If the number of nodes is odd, last node is duplicated while calculating next level up:
+     * Hash(LN) = Hash(LN+LN)
+     * @param {[]} array - Array of inputs. Each value must be a string/number/object.
+     * @param {Object} options - Additional options: {inputHash, hash}
+     * inputHash: - string 
+     *              ex: 'sha256' | 'md5' 
+     *              (*listOfSupportedHashes = crypto.getHashes())
+     * 
+     *            - function
+     *              ex:
+     *              function sha256(data) {
+     *                   return crypto.createHash('sha256').update(data).digest('hex')
+     *               }
+     *               
+     * @example
+     * ```js
+     * const tree = new MerkleTree([1,2,3,4,5,6], {hash: 'md5'})
+     * ```
+     */
+
+    constructor (array, option = {}) {
+        if (!array) {
+            array = []
+        } else {
+            if (!Array.isArray(array)) {
+                throw new Error('Input has to be an array')
+            }
+        }
+
+        if (option.constructor !== Object) {
+            throw new Error('Invalid option object: has to be {hash, inputHash}')
+        }
+        
+        this.option = {
+            hash: option.hash || 'sha256',
+            inputHash: option.inputHash || 'sha256'
+        }
+        this.originalArray = array
+        this.buildTree()
+    }
+
+}
+
+module.exports = MerkleTree