JavaScript Data Structures: Hash Table: Setup

Intro 🌐

Last time, we learned how to handle hash collisions.

Today, we'll use all of the stuff we learned so far to setup our Hash Table.

Requirements 💭

We need the following parts to setup our Hash Table:

• a Hash Table class
• a container for our data
• the size of the data
• a hash function that inputs a key and outputs an array index

Implementation ⛑

// a Hash Table class
class Hashtable {
  constructor() {
    // a container for our data
    this.data = []

    // the size of the data
    this.size = 0
  }

  // a hash function that inputs a key and outputs an array index
  hash(key) {
    const chars = key.split('')
    const charCodes = chars.map(char => char.charCodeAt())
    const charCodeSum = charCodes.reduce((acc, cur) => acc + cur)
    return charCodeSum
  }
}

If you are not familiar with the hash function, re-read this post.

Result

// create a new hash table
const newHashtable = new Hashtable()

// hash table should have no data and size 0
console.log(newHashtable)
// Hashtable { data: [], size: 0 } ✅

Next Part ➡️

We'll learn how to add data to our Hash Table.

Need some mentoring? Click here!

Further Reading 📖

• Simple Wiki: Hash Table
• Wikipedia: Hash Table
• Wikibooks: Hash Table

Questions ❔

• How would you implement the Hash Table?
• How would you build the hash function? Why?