TypeScript VS JavaScript : Key Differences You Must Know

Hardik Thakker

Founder & CEO

Published On: Mar 27, 2023

TypeScript and JavaScript are the two leading technologies that play a vital role in web application development. As a result, JavaScript has been the most popular programming language among the developer’s large community.

But, with the invention of TypeScript, the picture has changed completely. Do you know how? TypeScript is considered the enhanced version of JavaScript with some additional features.

In this blog, we will explore the differences between TypeScript vs JavaScript in detail. We will start by explaining the basics of each language and their respective features. Then, we will compare the two languages based on their performance, scalability, maintainability, and other factors. Finally, we will discuss some use cases for each language and provide tips on choosing the right language for your project.

Key Takeaways

Understanding the Concept of Static and Dynamic Languages

Static and dynamic are terms used to describe web application programming languages based on how they handle data types and variable declarations during compilation or runtime. A static language is one in which the data types of variables are determined at compile-time and cannot be changed during runtime.

In other words, the variable type is declared when the code is written, and the compiler checks to ensure that the variable is used correctly. If there is a mismatch between the type of a variable and the operation performed on it, the code will not compile. Examples of static languages include Java, C++, and TypeScript.

On the other hand, a dynamic language is one in which the data types of variables are determined at runtime, and variables can change their types during execution. In other words, variables are not declared with a specific type and can be used in any way.

The interpreter or runtime environment checks the type of a variable only when it is used. If there is a type mismatch between the variable and the operation, the program throws a runtime error. Examples of dynamic languages include JavaScript, Python, and Ruby.

The choice between static and dynamic languages depends on the project’s needs. For example, static languages can catch more errors at compile-time, making it easier to write and maintain larger and more complex codebases.

They can also provide better performance since the compiler can optimize the code based on the specific data types used. However, they may require more code to be written due to the need to declare variable types explicitly.

On the other hand, dynamic languages can be faster to develop since they require fewer explicit type declarations and can be easier to read and understand. As a result, they are often used for scripting and web development, where rapid prototyping and flexibility are essential. However, they may be more prone to runtime errors due to the lack of type checking at compile time.

What is JavaScript?

JavaScript is a client-side and server-side language. The primary reason that JavaScript is a scripting and interpreted language is that it’s not compiled before execution. Instead, the primary usage of JavaScript is to create dynamic web pages.

Javascript offers HTML and CSS as two major languages that provide structure and style to web pages. On the other hand, JavaScript is a popular scripting language that will provide you to create interactive web pages with responsive elements that improve user engagement.

And if we talk about the history of JavaScript, it was originally developed by Brendan Eich of Netscape Communications Corporation, initially called Mocha, then LiveScript, and finally a new language in the newer versions renamed to JavaScript.

What Is JavaScript Used For?

Javascript is one of the best scripting languages used explicitly by developers globally for creating dynamic and interactive web content-like applications.  Almost 97% of all websites primarily use JavaScript as a popular scripting language. So, if you have basic scripting knowledge, you can quickly build responsive web apps for your business needs.

JavaScript offers you to develop different applications like software, hardware controls, and servers. In addition, due to its native behavior to the web browser, JavaScript is considered a well-known web-based language.

JavaScript is used for:

• Easily adding impressive behavior to create interactive web pages.
• Creating web and mobile apps.
• Building web servers and developing server applications.
• Speeding up the performance of the application.
• Developing front-end development as well as back-end development.
• Performing the data structure and reference validation on the web browser itself.

Related Post: Angular vs React

What is TypeScript?

Developed by Microsoft, TypeScript is an open-source programming language that quickly compiles to JavaScript. TypeScript is not just a scripting language but also a set of tools that help you make web development easier.

From the above diagram, we can easily see that TypeScript is JavaScript with added features designed explicitly to overcome JavaScript data grid libraries setbacks. TypeScript is beneficial to many developers to have basic scripting knowledge regarding static type definitions, Javascript libraries, and handling code complexity. And it plays a major role in understanding the difference between TypeScript vs. JavaScript.

And it plays a major role in understanding the difference between TypeScript vs. JavaScript.

What is TypeScript Used For?

TypeScript is a superset of typed JavaScript that allows developers to build and manage large-scale JavaScript projects. In simple words, we can say that Typescript supports JS libraries with additional features like strong & optional static typing, code compilation, and object-oriented programming.

TypeScript is used for:

• Simplifying JavaScript code, making your application easier to read and debug.
• Quickly building web applications using highly productive web development tools for JavaScript IDEs and practices, like static checking.
• Quickly coding for all complex and large applications.
• Availing all the benefits of ES6 (ECMAScript 6), static typing plus more productivity.
• You can developed mobile and web applications with TypeScript web development company.

What are the Different Types of TypeScript?

TypeScript is a powerful and intuitive language that specifically contains various basic types, such as Number, Array, Tuple, Boolean, String, and many more.

It’s a fact that some of these essential types are not available in JavaScript. If you want to know more about such types of TypeScript, you can visit the official TypeScript documentation.

Furthermore, below are some other types that are expressivity of TypeScript:

1. Any & Unknown

   Any (anything that you wish) is best used for covering unknown is its type-safe system. The primary usage of any is to allow the developers to easily assign JavaScript variables to the code. It’s widely used to describe incoming variables that are not yet being validated and whose type definitions is unknown.

   And if we talk about Unknown, it’s exactly similar to Any, but it will not allow you to do anything with it unless it’s explicitly type-checked in your TypeScript development.

2. Void

   Void is specifically used by developers when there is no value returned. Generally, it’s used for the return type of function that returns nothing.

3. Never

   If something is never going to happen, we can use Never as the return type. One such good example is an exception-throwing function directly into the TypeScript code.

4. Intersection & Union Types

   This option allows the developers to easily create custom types as per the code logic. Intersection types let you combine several basic types into one type.

   Let’s say, we have custom type Employee which contact empl_fname:string and empl_fname:string. And you want to convert this type to this and that.

   Union types allow you to type to take one of the various basic types.

   For example, if developers pass a query that returns either result:string or undefined, we can definitely say that this TypeScript code type needs to be converted to this or that.

   All of these sorts make sense when you think of them as spaces.

How Does TypeScript Differ from JavaScript?

As stated earlier, TypeScript has additional features compared to JavaScript programming language. In simple words, TypeScript is an object-oriented programming language, whereas JavaScript is a scripting language.

This superset of javascript is one programming language bundled up with multiple interfaces and modules through ES6 features; however, JavaScript doesn’t offer such features. In short, Typescript supports interfaces that makes the programming easier.

Moreover, this object-oriented language is strongly-entered, or we can say that TypeScript supports static typing. This means static type checking offers the best accuracy at the time of compilation.

TypeScript highlights the compilation errors at the time of development. Due to this, the scope of examining and getting runtime errors is very low. On the contrary, JavaScript is an interpreted language.

TypeScript is nothing but a superset of javascript and some added features, that is, ES6 features. Therefore, many Javascript developers do not prefer to keep it in their targeted web browser support, but the typescript compiler can compile .ts files into ECMAScript.

TypeScript VS JavaScript: Pros and Cons

Pros and Cons of TypeScript

Pros and Cons of JavaScript

TypeScript vs JavaScript Examples

Here we are bringing TypeScript vs JavaScript examples. Now, we will focus on some code snippets to differentiate between TypeScript and JavaScript.

Have a look at the simple and valid JavaScript code snippet:

let var1 = “Welcome to Albiorix”;
var1 = 30;
console.log(var1);

Here, we can see that var1 is a string, then becomes a number.

As we know that JavaScript works on the concept that is only a loosely typed programming language, it becomes easy for software developers to redefine var1 as a variable of any type—from a string to a function—at any time.

So, the output of the code becomes 10.

Now, we will convert the same code to TypeScript:

let var1: string = “Welcome to Albiorix”;
var1 = 10;
console.log(var1);

Likewise, var1 is declared to be a string. And we are trying to assign a number to var1. This is the code structure that is strictly not allowed by TypeScript’s strict type system. Obviously, the transpiling results in an error:

TSError: ⨯ Unable to compile TypeScript:
src/snippet1.ts:2:1 – error TS2322: Type ‘number’ is not assignable to type ‘string’.2 var1 = 10;

If we want to make the same JavaScript code to behave the same like TypeScript, it becomes mandatory to inform transpiler to treat the original JavaScript snippet as if it were TypeScript. So, it becomes the prime responsibility of the transpiler to automatically infer that var1 should be a string | number.

This is a TypeScript union type, which allows us to assign var1 a string or a number at any time. Having resolved the type conflict, our TypeScript code would transpile successfully. Executing it would produce the same result as the JavaScript example.

Validation in TypeScript vs. JavaScript

In JavaScript, validation is typically done using conditional statements and regular expressions. For example, to validate an email address, you might use a regular expression to check if the input matches the format of an email address. If it does not match, you can display an error message to the user. This approach requires careful handling of edge cases and can be error-prone.

In TypeScript, validation is more robust and type-safe due to its static typing feature. TypeScript provides various built-in types such as string, number, boolean, etc., which can be used to define the type of variables and function parameters.

This makes it easier to catch type errors during compilation and prevents them from propagating to runtime. In addition, TypeScript provides interfaces, classes, and decorators that can be used to define custom types and validate their properties.

For example, you can define an interface for an object representing a user and validate its properties as follows:

interface User {
  id: number;
  name: string;
  email: string;
}

function validateUser(user: User) {
  if (!user.id) {
    throw new Error("User ID is required");
  }
  if (!user.name) {
    throw new Error("User name is required");
  }
  if (!user.email.match(/^[^\s@]+@[^\s@]+\.[^\s@]+$/)) {
    throw new Error("Invalid email address");
  }
}

const user: User = { id: 1, name: "John Doe", email: "john.doe@example.com" };
validateUser(user);

In this example, we define an interface User with properties id, name, and email. We then define a function validateUser that takes a User object and checks if its properties are valid. If any property is missing or invalid, the function throws an error. Finally, we create a User object and validate it using the validateUser function.

Overall, while both TypeScript and JavaScript support validation, TypeScript provides a more type-safe and robust approach due to its static typing feature and built-in types.

Difference Between Typescript and Javascript: The Comparison Table

After having a look at the basics of TypeScript and JavaScript, it’s time to see the concept of comparing Typescript with JavaScript. So, let’s explore the difference between JavaScript and TypeScript in the form of a comparison table.

When to Choose JavaScript and TypeScript?

In the comparison of the difference between JavaScript VS Typescript, it’s time to explore the situation for the fresher or experienced developers to select TypeScript or JavaScript for their project requirements.

You can opt for the TypeScript programming language when

• Compile Time Type Checking: TypeScript usually supports Vanilla JavaScript, and in such cases, type verification is performed at runtime. It eventually adds to the runtime overhead into the code, which may be avoided by conducting compile-time validation.
• Large-Scale Projects: As compared to Javascript, TypeScript is a language that is designed explicitly to develop large scale applications that run seamlessly or when many Typescript developers are working together.
• Easy to Use:If any Javascript developers is involved in React or Node JS development and is not familiar with its APIs, you can utilize IntelliSense, which helps them identify and navigate new interfaces in the newer versions. However, they both offer type definitions.

On the other hand, JavaScript helps you when

• Small Projects: JavaScript language is a perfect choice if you are dealing with small scale projects or with fewer codes available on the project.
• Active Framework Support: If TypeScript does not support any common framework like EmberJS or Node JS, then the developers might not be able to leverage all the JS features into the same code.
• Build Tools:When the professionals need to generate the final run of the JavaScript, TypeScript requires a build step. However, developing JavaScript applications without any build tools is becoming increasingly unusual.
• Testing Workflow: If JavaScript experts are involved in utilizing test-driven web development project, the benefits of switching to TypeScript may not be enough to justify the expenditures.

TypeScript VS JavaScript: Which is Better?

Selecting TypeScript over JavaScript makes it easy for the developers to deal with removing certain software anomalies during the web development project phase. Moreover, you can easily secure the source code before going into production.

In this article on the difference between TypeScript vs JavaScript, we have seen the overall concept of the available essential features of both technologies. Moreover, we came across the various optional parameters or terminology on how Javascript and Typescript differ.