Hash Table In Javascript

A hash table is a data structure used to store key-value pairs efficiently. In JavaScript, you can implement a hash table using objects. This is a great way to quickly access and update data based on a specific key.

To create a hash table in JavaScript, you can simply use an object:

const hashTable = {};

In this hash table, you can store key-value pairs like this:

hashTable["name"] = "Alice";
hashTable["age"] = 30;

To retrieve data from the hash table, you can access it directly using the key:

console.log(hashTable["name"]); // Output: Alice
console.log(hashTable["age"]); // Output: 30

One important advantage of using a hash table is the constant time complexity for both insertion and retrieval operations. This makes hash tables a fast and efficient way to manage data.

When it comes to handling collisions in hash tables, JavaScript's built-in method of handling collisions is through chaining. Chaining means that each key in the hash table points to a linked list of key-value pairs.

// Implementing chaining in a hash table
const hashTable = {};

function addKeyValuePair(key, value) {
  const hashedKey = hash(key);
  if (!hashTable[hashedKey]) {
    hashTable[hashedKey] = [];
  }
  hashTable[hashedKey].push({ key, value });
}

function getValueByKey(key) {
  const hashedKey = hash(key);
  if (!hashTable[hashedKey]) {
    return null;
  }
  const list = hashTable[hashedKey];
  for (const pair of list) {
    if (pair.key === key) {
      return pair.value;
    }
  }
  return null;
}

In this implementation, we first hash the key to get the hashed key. If the hashed key doesn't exist in the hash table, we create an empty array for it. When adding a key-value pair, we push it into the array. When retrieving a value by key, we search through the linked list to find the matching key.

In summary, hash tables in JavaScript are a powerful way to store and access data using key-value pairs efficiently. They provide constant time complexity for insertion and retrieval operations, making them a valuable tool in software development.

Remember to consider collision handling techniques like chaining when working with hash tables to ensure data integrity and efficient access to your stored values.