Data Structures: Create a Hash Table - freeCodeCamp

hashtable.js

var called = 0;
var hash = string => {
  called++;
  var hash = 0;
  for (var i = 0; i < string.length; i++) {
    hash += string.charCodeAt(i);
  }
  return hash;
};
var HashTable = function() {
  this.collection = {};
  // change code below this line

  this.add = (key, value) => {
    let hashIndex = hash(key);
    if (!this.collection[hashIndex]) {
      this.collection[hashIndex] = {};
    }

    this.collection[hashIndex][key] = value;
  };
  this.remove = key => {
    let hashIndex = hash(key);
    if (!this.collection[hashIndex]) {
      return null;
    }

    let objKeys = Object.keys(this.collection[hashIndex]);
    for (let value of objKeys) {
      if (value === key) {
        delete this.collection[hashIndex];

        // Here, I was trying to delete the particular value from the hashIndex like
        // delete this.collection[hashIndex][value];
        // But, It seems like, we need to delete the whole index if there are no values in hashIndex.
      }
    }
  };
  this.lookup = key => {
    let hashIndex = hash(key);
    if (!this.collection[hashIndex]) {
      return null;
    }

    let objKeys = Object.keys(this.collection[hashIndex]);
    for (let value of objKeys) {
      if (value === key) {
        return this.collection[hashIndex][value];
      }
    }
  };
  // change code above this line
};