hashTable.js

// Hash map key string to any value
// Overwrite on collision
class HashTable1 {
  constructor (size = 100) {
    this._storage = []
    this._storageSize = size
  }

  // Hash a key string to an index number
  _hashFunction (key) {
    let sum = 0
    for (let i = 0; i < key.length; i += 1) {
      sum += key.charCodeAt(i) * 3
    }
    return sum % this._storageSize
  }

  insert (key, value) {
    const index = this._hashFunction(key)
    this._storage[index] = value
    return value
  }

  remove (key) {
    const index = this._hashFunction(key)
    const value = this._storage[index]
    delete this._storage[index]
    return value
  }

  retrieve (key) {
    const index = this._hashFunction(key)
    const value = this._storage[index]
    return value
  }
}

// Hash map key string to any value
// Build array of collisions
// class HashTable2

// Hash map key string to any value
// Build linked list of collisions
// class HashTable3

const hashTable1 = new HashTable1(100)
console.log(hashTable1._storage)

hashTable1.insert('a', 'apple')
hashTable1.insert('b', 'banana')
hashTable1.insert('c', 'cherry')
console.log(hashTable1.retrieve('a'))
console.log(hashTable1.retrieve('b'))
console.log(hashTable1.retrieve('c'))
console.log(hashTable1.retrieve('d'))
console.log(hashTable1._storage)

hashTable1.remove('a')
hashTable1.remove('b')
hashTable1.remove('d')
console.log(hashTable1.retrieve('a'))
console.log(hashTable1.retrieve('b'))
console.log(hashTable1.retrieve('c'))
console.log(hashTable1.retrieve('d'))

console.log(hashTable1._storage)