The Dictionary Class in Javascript

JavaScript doesn't have a built-in Dictionary class, but we can create our own using objects or the Map class. Here's a complete implementation of a custom Dictionary class called MyMap.

Complete Dictionary Implementation

class MyMap {
   constructor() {
      this.container = {};
   }
   
   display() {
      console.log(this.container);
   }
   
   hasKey(key) {
      return key in this.container;
   }
   
   put(key, value) {
      this.container[key] = value;
   }
   
   delete(key) {
      if (this.hasKey(key)) {
         delete this.container[key];
         return true;
      }
      return false;
   }
   
   get(key) {
      return this.hasKey(key) ? this.container[key] : undefined;
   }
   
   keys() {
      return Object.keys(this.container);
   }
   
   values() {
      let values = [];
      for (let key in this.container) {
         values.push(this.container[key]);
      }
      return values;
   }
   
   clear() {
      this.container = {};
   }
   
   forEach(callback) {
      for (let prop in this.container) {
         callback(prop, this.container[prop]);
      }
   }
}

Using the Dictionary

// Create a new dictionary
let myDict = new MyMap();

// Add key-value pairs
myDict.put("name", "John");
myDict.put("age", 30);
myDict.put("city", "New York");

// Display the dictionary
myDict.display();

// Get values
console.log("Name:", myDict.get("name"));
console.log("Age:", myDict.get("age"));

// Check if key exists
console.log("Has 'email':", myDict.hasKey("email"));
console.log("Has 'name':", myDict.hasKey("name"));

{ name: 'John', age: 30, city: 'New York' }
Name: John
Age: 30
Has 'email': false
Has 'name': true

Dictionary Operations

let dict = new MyMap();
dict.put("apple", 5);
dict.put("banana", 3);
dict.put("orange", 8);

// Get all keys and values
console.log("Keys:", dict.keys());
console.log("Values:", dict.values());

// Use forEach to iterate
console.log("Iterating through dictionary:");
dict.forEach((key, value) => {
   console.log(`${key}: ${value}`);
});

// Delete a key
console.log("Deleted 'banana':", dict.delete("banana"));
dict.display();

Keys: [ 'apple', 'banana', 'orange' ]
Values: [ 5, 3, 8 ]
Iterating through dictionary:
apple: 5
banana: 3
orange: 8
Deleted 'banana': true
{ apple: 5, orange: 8 }

Key Features

Conclusion

This custom MyMap class provides dictionary functionality in JavaScript with methods for adding, retrieving, and managing key-value pairs. It's a useful alternative when you need dictionary-like behavior with custom methods.