In JavaScript, dictionaries are implemented using objects. A dictionary, also known as a map, is a collection of key-value pairs. You can create a dictionary dynamically by defining an empty object and then adding key-value pairs using various methods. This article covers multiple approaches for dynamically creating and modifying dictionaries in JavaScript.

Below are the approaches for creating a dictionary and adding key-value pairs dynamically:

Using Object Literal Notation

Create a dictionary by defining an empty object and assigning key-value pairs using bracket or dot notation. This method provides a straightforward way to dynamically add and modify key-value pairs.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

   // Using object literal notation
   let dictionary = {};
   dictionary["key1"] = "value1";
   dictionary["key2"] = "value2";
   console.log(dictionary);

{ key1: 'value1', key2: 'value2' }

Using Object Constructor

Use the Object constructor to create a dictionary. Key-value pairs are added dynamically by assigning values to object properties. This approach is similar to object literal notation but uses a constructor function.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

let dictionary = new Object();
dictionary["key1"] = "value1";
dictionary["key2"] = "value2";
console.log(dictionary);

{ key1: 'value1', key2: 'value2' }

Using ES6 Map

Create a dictionary using the Map object provided by ES6. Key-value pairs are added dynamically using the set() method. Maps offer built-in methods for adding, retrieving, and deleting key-value pairs, providing flexibility and functionality.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

let dictionary = new Map();
dictionary.set("key1", "value1");
dictionary.set("key2", "value2");
console.log(dictionary);

Map(2) { 'key1' => 'value1', 'key2' => 'value2' }

Using Object.assign()

Combine an existing dictionary with new key-value pairs using Object.assign(). This method copies the values of all enumerable own properties from one or more source objects to a target object. It is particularly useful for merging dictionaries dynamically.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

// Using Object.assign()
let dictionary = {};
Object
    .assign(dictionary, { "key1": "value1", "key2": "value2" });
console.log(dictionary);

{ key1: 'value1', key2: 'value2' }

Using Spread Operator

Utilize the spread operator to dynamically add key-value pairs to a dictionary. This operator allows for the creation of a new object with properties copied from another object, enabling the dynamic addition of key-value pairs without mutating the original dictionary.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

   // Using Spread Operator
   let dictionary = {};
   dictionary = { ...dictionary, "key1": "value1", "key2": "value2" };
   console.log(dictionary);

{ key1: 'value1', key2: 'value2' }

Using Bracket Notation

Add key-value pairs to a dictionary dynamically using bracket notation. This approach involves accessing and modifying object properties using square brackets and allows for the dynamic creation of keys based on variables or expressions.

Example:To demonstrate creating a dictionary and add key-value pairs dynamically.

  // Using bracket notation
  let dictionary = {};
  let key = "key1";
  let value = "value1";
  dictionary[key] = value;
  console.log(dictionary);

{ key1: 'value1' }

Using Dot Notation

Dynamically add key-value pairs to a dictionary using dot notation. This method involves directly assigning values to object properties using dot notation and is commonly used when the keys are known in advance.

Example: To demonstrate creating a dictionary and add key-value pairs dynamically.

   // Using dot notation
   let dictionary = {};
   dictionary.key1 = "value1";
   dictionary.key2 = "value2";
   console.log(dictionary);

{ key1: 'value1', key2: 'value2' }

Additional Tips:

• Choosing Between Objects and Maps: Use objects when you need a simple key-value pair storage. Opt for Map when you require keys of any type, ordered storage, or specific built-in methods.
• Avoid Key Collisions: When using objects, avoid keys that clash with built-in object properties (e.g., toString). Map does not have this issue.
• Performance Considerations: Maps are generally more performant when frequent additions and deletions are needed.

These methods provide flexible ways to dynamically create and manipulate dictionaries in JavaScript.