JavaScript vs. TypeScript: Which Should You Choose?

JavaScript and TypeScript are two of the most popular programming languages in the web development world. JavaScript has been the cornerstone of web development for decades, enabling dynamic and interactive web pages. TypeScript, on the other hand, is a relatively new language developed by Microsoft that builds on top of JavaScript. In this blog post, we’ll explore the fundamental concepts, usage methods, common practices, and best practices of both languages to help you decide which one is the right choice for your project.

Table of Contents

  1. Fundamental Concepts
  2. Usage Methods
  3. Common Practices
  4. Best Practices
  5. Conclusion
  6. References

Fundamental Concepts

JavaScript

JavaScript is a high - level, dynamic, untyped, and interpreted programming language. It is primarily used for creating interactive web pages and web applications. JavaScript is a multi - paradigm language, supporting object - oriented, imperative, and functional programming styles.

One of the key features of JavaScript is its dynamic typing. Variables in JavaScript do not need to be declared with a specific type, and their type can change during the execution of the program. For example:

let num = 10;
num = "Hello";

TypeScript

TypeScript is a superset of JavaScript. It adds static typing to JavaScript, which means that variables, function parameters, and return values can be explicitly typed. TypeScript code is transpiled into plain JavaScript code, which can then be run in any JavaScript environment.

Here is an example of a TypeScript variable with a type annotation:

let num: number = 10;
// The following line will cause a compilation error because we are trying to assign a string to a number variable
// num = "Hello";

Usage Methods

JavaScript Usage

JavaScript can be used in several ways:

  • Inline in HTML: You can write JavaScript code directly inside HTML files using the <script> tag.
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF - 8">
</head>

<body>
    <button id="myButton">Click me</button>
    <script>
        const button = document.getElementById('myButton');
        button.addEventListener('click', function () {
            alert('Button clicked!');
        });
    </script>
</body>

</html>
  • External File: You can also write JavaScript code in a separate .js file and link it to your HTML file.
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF - 8">
    <script src="script.js"></script>
</head>

<body>
    <button id="myButton">Click me</button>
</body>

</html>

And in script.js:

const button = document.getElementById('myButton');
button.addEventListener('click', function () {
    alert('Button clicked!');
});

TypeScript Usage

To use TypeScript, you first need to install it globally using npm:

npm install -g typescript
  1. Create a TypeScript file: Create a file with a .ts extension, for example, app.ts.
function greet(name: string): string {
    return `Hello, ${name}!`;
}

const message = greet('John');
console.log(message);
  1. Transpile TypeScript to JavaScript: Use the tsc command to transpile your TypeScript code to JavaScript.
tsc app.ts

This will generate an app.js file, which can be run in a JavaScript environment.

Common Practices

JavaScript Common Practices

  • Use Strict Mode: Enabling strict mode helps you write more secure and error - free code by throwing errors for some common programming mistakes.
'use strict';
let x = 10;
// The following line will throw an error in strict mode because 'y' is not declared
// y = 20;
  • Modular Programming: Use modules to organize your code into smaller, reusable pieces. In modern JavaScript, you can use the import and export syntax.
// math.js
export function add(a, b) {
    return a + b;
}

// main.js
import { add } from './math.js';
const result = add(5, 3);
console.log(result);

TypeScript Common Practices

  • Interface Definition: Use interfaces to define the shape of objects.
interface Person {
    name: string;
    age: number;
}

function printPerson(person: Person) {
    console.log(`${person.name} is ${person.age} years old.`);
}

const john: Person = { name: 'John', age: 30 };
printPerson(john);
  • Type Guards: Use type guards to narrow down the type of a variable within a conditional block.
function printValue(value: string | number) {
    if (typeof value === 'string') {
        console.log(`The string is: ${value}`);
    } else {
        console.log(`The number is: ${value}`);
    }
}

printValue('Hello');
printValue(10);

Best Practices

JavaScript Best Practices

  • Error Handling: Use try...catch blocks to handle errors gracefully.
try {
    const result = JSON.parse('{ "name": "John" }');
    console.log(result);
} catch (error) {
    console.error('Error parsing JSON:', error);
}
  • Event Delegation: When dealing with multiple elements that require event handling, use event delegation to reduce the number of event listeners.
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF - 8">
</head>

<body>
    <ul id="myList">
        <li>Item 1</li>
        <li>Item 2</li>
        <li>Item 3</li>
    </ul>
    <script>
        const list = document.getElementById('myList');
        list.addEventListener('click', function (event) {
            if (event.target.tagName === 'LI') {
                console.log(`Clicked on ${event.target.textContent}`);
            }
        });
    </script>
</body>

</html>

TypeScript Best Practices

  • Use Union and Intersection Types: Union types allow a variable to have one of several types, while intersection types combine multiple types into one.
type Admin = {
    name: string;
    role: 'admin';
};

type User = {
    name: string;
    role: 'user';
};

type AdminOrUser = Admin | User;

function printRole(person: AdminOrUser) {
    console.log(`${person.name} has role: ${person.role}`);
}

const admin: Admin = { name: 'Alice', role: 'admin' };
const user: User = { name: 'Bob', role: 'user' };
printRole(admin);
printRole(user);
  • Separate Type Definitions: Keep your type definitions in separate files to make your code more organized and maintainable.

Conclusion

The choice between JavaScript and TypeScript depends on the nature of your project. If you are working on a small - scale project or need quick prototyping, JavaScript might be the better choice due to its simplicity and immediate availability. However, for large - scale, complex projects where code maintainability, type safety, and developer productivity are crucial, TypeScript is a great option. TypeScript’s static typing helps catch errors early in the development process and makes the codebase more understandable and refactorable.

References