hashTable.js

function HashTable(size) {
    this.buckets = Array(size);
    this.numBuckets = this.buckets.length;
}

function HashNode(key, value, next) {
    this.key = key;
    this.value = value;
    this.next = next || null;
}

HashTable.prototype.hash = function(key) {
  let total = 0;
  for (let i = 0; i < key.length; i++) {
    total += key.charCodeAt(i);
  }
  let bucket = total % this.numBuckets;
  return bucket;
}

HashTable.prototype.insert = function(key, value) {
  let index = this.hash(key);
  if (!this.buckets[index]) this.buckets[index] = new HashNode(key, value);
  else {
    let currentNode = this.buckets[index];
    while (currentNode.next) {
      currentNode = currentNode.next;
    }
    currentNode.next = new HashNode(key, value);
  }
}

let myHT = new HashTable(30);

myHT.insert('Dean', 'dean@gmail.com');
myHT.insert('Megan', 'megan@gmail.com');
myHT.insert('Dane', 'dane@yahoo.com');

console.log(myHT.buckets);