The Hashmap class is a simple implementation of a hashmap in JavaScript. It is a wrapper around the native Map class.

© HandyScript HashMap 5/27/23 - Last Update: 9/25/23:

• Handy Script Hashmap
  • Table of Contents
  • Methods
    • constructor
    • get
    • put
    • update
    • upsert
    • remove
    • contains
    • includes
    • keys
    • values
    • size
    • clear
    • isEmpty
    • forEach
    • filter
    • entries
    • toObject
    • toArray
    • toFlatArray
    • getKeyByValue
    • getKeysByValue
    • updateKeyByValue

The constructor method creates a new Hashmap object.

constructor(obj?: Record<string, unknown>): Hashmap

Parameters:

• obj - The object to initialize the hashmap with. (Optional)

Returns: Hashmap - The new Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap);  // Hashmap { a: 1, b: 2, c: 3 }

The get method returns the value of the given key.

Hashmap.prototype.get(key: string): unknown

Parameters:

• key - The key to get the value of.

Returns: unknown - The value of the given key.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.get('a'));  // 1

The put method adds a new key-value pair to the Hashmap object.

Hashmap.prototype.put(key: string, value: unknown): Hashmap

Parameters:

• key - The key to set the value of.
• value - The value to set the key to.

Returns: Hashmap - The Hashmap object with the new key-value pair.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.put('d', 4);
console.log(hashmap);  // Hashmap { a: 1, b: 2, c: 3, d: 4 }

The update method updates the value of the given key.

⚠️ Note: It will throw an error if the key does not exist.

Hashmap.prototype.update(key: string, value: unknown): Hashmap

Parameters:

• key - The key to update the value of.
• value - The value to update the key to.

Returns: Hashmap - The Hashmap object with the updated key-value pair.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.update('a', 4);
console.log(hashmap)  // Hashmap { a: 4, b: 2, c: 3, d: 4 }

The upsert method updates the value of the given key if it exists, otherwise it adds a new key-value pair.

Hashmap.prototype.upsert(key: string, value: unknown): Hashmap

Parameters:

• key - The key to update the value of.
• value - The value to update the key to.

Returns: Hashmap - The Hashmap object with the upserted key-value pair.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.upsert('a', 4);
hashmap.upsert('d', 4);
console.log(hashmap)  // Hashmap { a: 4, b: 2, c: 3, d: 4 }

The remove method removes the given key-value pair from the Hashmap object.

Hashmap.prototype.remove(key: string): boolean

Parameters:

• key - The key to remove the value of.

Returns: boolean - returns true if an element in the Hashmap existed and has been removed, or false if the element does not exist.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.remove('a'); // true
console.log(hashmap)  // Hashmap { b: 2, c: 3 }

The contains method checks if the Hashmap object contains all the given keys.

Hashmap.prototype.contains(...keys: string[]): boolean

Parameters:

• keys - The keys to check if they exist in the Hashmap object.

Returns: boolean - returns true if the Hashmap object contains the given keys, otherwise false.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.contains('a', 'b'); // true
hashmap.contains('a', 'd'); // false

The includes method checks if the Hashmap object contains any of the given keys.

Hashmap.prototype.includes(...keys: string[]): boolean

Parameters:

• keys - The keys to check if they exist in the Hashmap object.

Returns: boolean - returns true if the Hashmap object includes the given keys, otherwise false.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.includes('a', 'b'); // true
hashmap.includes('a', 'd'); // true
hashmap.includes('d', 'e'); // false

The keys method returns an array of the keys in the Hashmap object.

Hashmap.prototype.keys(): string[]

Returns: string[] - An array of the keys in the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.keys()); // [ 'a', 'b', 'c' ]

The values method returns an array of the values in the Hashmap object.

Hashmap.prototype.values(): unknown[]

Returns: unknown[] - An array of the values in the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.values()); // [ 1, 2, 3 ]

The size method returns the number of key-value pairs in the Hashmap object.

Hashmap.prototype.size(): number

Returns: number - The number of key-value pairs in the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.size()); // 3

The clear method removes all key-value pairs from the Hashmap object.

Hashmap.prototype.clear(): void

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.clear();
console.log(hashmap); // Hashmap {}

The isEmpty method checks if the Hashmap object is empty.

Hashmap.prototype.isEmpty(): boolean

Returns: boolean - returns true if the Hashmap object is empty, otherwise false.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.isEmpty()); // false
hashmap.clear();
console.log(hashmap.isEmpty()); // true

The forEach method executes a provided function once for each key-value pair in the Hashmap object.

Hashmap.prototype.forEach(callback: (value: unknown, key: string) => void): void

Parameters:

• callback - Function to execute for each key-value pair. The callback is invoked with three arguments: the value of the key-value pair, the key of the key-value pair, and the Hashmap object being traversed.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
hashmap.forEach((value, key) => {
  console.log(key, value);
});

The filter method creates a new Hashmap object with all key-value pairs that pass the test implemented by the provided function.

Hashmap.prototype.filter(callback: (value: unknown, key: string) => boolean): Hashmap

Parameters:

• callback - Function to test each key-value pair of the Hashmap object. The callback is invoked with three arguments: the value of the key-value pair, the key of the key-value pair, and the Hashmap object being traversed.

Returns: Hashmap - A new Hashmap object with the key-value pairs that pass the test. If no key-value pairs pass the test, an empty Hashmap object will be returned.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
const filtered = hashmap.filter((value, key) => {
  return value > 1;
});
console.log(filtered); // Hashmap { b: 2, c: 3 }

The entries method returns an array of the key-value pairs in the Hashmap object.

Hashmap.prototype.entries(): [string, unknown][]

Returns: [string, unknown][] - An array of the key-value pairs in the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.entries()); // [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', 3 ] ]

The toObject method returns a plain object representation of the Hashmap object.

Hashmap.prototype.toObject(): Record<string, unknown>

Returns: Record<string, unknown> - A plain object representation of the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.toObject()); // { a: 1, b: 2, c: 3 }

The toArray method returns an array representation of the Hashmap object.

Hashmap.prototype.toArray(): [string, unknown][]

Returns: [string, unknown][] - An array representation of the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.toArray()); // [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', 3 ] ]

The toFlatArray method returns a flattened array representation of the Hashmap object.

Hashmap.prototype.toFlatArray(): [string, unknown]

Returns: [string, unknown] - A flattened array representation of the Hashmap object.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.toFlatArray()); // [ 'a', 1, 'b', 2, 'c', 3 ]

The getKeyByValue method returns the key of the given value.

⚠️ Note: If 2 or more keys have the same value, the first key will be returned.

Hashmap.prototype.getKeyByValue(value: unknown): string | null

Parameters:

• value - The value to get the key of.

Returns: string | null - The key of the given value, or null if the value does not exist.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3 });
console.log(hashmap.getKeyByValue(2)); // b
console.log(hashmap.getKeyByValue(4)); // null

The getKeysByValue method returns an array of keys of the given value.

Hashmap.prototype.getKeysByValue(value: unknown): string[]

Parameters:

• value - The value to get the keys of.

Returns: string[] - An array of keys of the given value, or an empty array if the value does not exist.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3, d: 2 });
console.log(hashmap.getKeysByValue(2)); // [ 'b', 'd' ]
console.log(hashmap.getKeysByValue(4)); // []

The updateKeyByValue method updates the key of the given value.

⚠️ Note: If 2 or more keys have the same value, the first key will be updated.

Hashmap.prototype.updateKeyByValue(value: unknown, key: string): void

Parameters:

• value - The value to update the key of.
• key - The key to update the value of.

Example:

const hashmap = new Hashmap({ a: 1, b: 2, c: 3, d: 2 });
hashmap.updateKeyByValue(2, 'e');
console.log(hashmap); // Hashmap { a: 1, e: 2, c: 3, d: 2 }

© HandyScript HashMap 5/27/23