In TypeScript, a dictionary typically refers to an object where the keys are of a consistent type (often strings or numbers) and the values can be of any type. As the dictionary is not supported by TpeScript natively. It’s similar to a hash map or associative array in other programming languages. Dictionaries allow you to store and retrieve data using keys, providing a flexible way to manage collections of data in TypeScript programs.

Prerequisites

• Node.js
• NPM

Steps to Implement Typescript Dictionary

Step 1: Initialize the Project

Create a new directory for your project and navigate into it:

mkdir typescript-dictionary-project
cd typescript-dictionary-project

Step 2: Initialize a new Node.js project:

npm init -y

Step 3: Install TypeScript

Install TypeScript as a dev dependency:

npm install typescript --save-dev

Folder Structure:

Dependencies:

"devDependencies": {
    "typescript": "^5.5.3"
  }

Step 4: Configure TypeScript

Create a tsconfig.json file in the project root with the following content:

{
  "compilerOptions": {
    "target": "ES6",
    "module": "commonjs",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["src"]
}

Step 5: Write TypeScript Code

The code defines a generic Dictionary<T> interface where keys are strings and values can be of any type T. It creates a Dictionary<number> instance, adds entries dynamically using a function addEntry, and outputs the updated dictionary with added key-value pairs.

Example: This example shows the creation of Dictionary using TypeScript.

// index.ts

interface Dictionary<T> {
    [key: string]: T;
}

const dictionary: Dictionary<number> = {
    "one": 1,
    "two": 2,
    "three": 3
};

const addEntry = (dict: Dictionary<number>,
    key: string, value: number): void => {
    dict[key] = value;
};

addEntry(dictionary, "four", 4);

console.log(dictionary);

Step 6: Compile and Run the Code

Compile the TypeScript code to JavaScript:

npx tsc

Run the generated JavaScript code:

node src/index.js

Output:

{
  "one": 1,
  "two": 2,
  "three": 3,
  "four": 4
}