TypeScript VS JavaScript : Key Differences You Must Know

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.

Before we understand the difference between TypeScript VS JavaScript, we need to understand the basic concepts of TypeScript and JavaScript.

What is JavaScript?

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

HTML and CSS are the 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 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.

JavaScript is a boon for developing 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 validation on the web browser itself rather than on the server.

Related Post: Angular vs React

What is TypeScript?

Developed by Microsoft, TypeScript is an open-source 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 libraries setbacks. TypeScript is beneficial to the developers to have basic scripting knowledge regarding static type definitions and handling code complexity.

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 it’s JavaScript with additional features like strong 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), 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 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.

Moreover, this object-oriented language is strongly-entered, or we can say that TypeScript supports static typing. This means static typing permits checking type accuracy at compile time.

TypeScript highlights the compilation errors at the time of development. Due to this, the scope of examining 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 JS developers do not prefer to keep it in their targeted web browser, 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 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.

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: TypeScript is a programming 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 the experts are involved in React or Node JS development and are not familiar with its APIs, you can utilize IntelliSense, which helps them identify and navigate new interfaces. 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 web projects or with fewer codes available on the project.
• Active Framework Support: If TypeScript does not support any common framework like EmberJS, then the developers might not be able to leverage all the features into the same code.
• Build Tools: When the professionals need to generate the final run of the JavaScript application, 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.

Hardik Thakker

Hardik Thakker is a Co-Founder & CEO at Albiorix Technology. Having more than 12+ years of experience in handling the development team at a pace, he is totally involved in managing the overall aspects of the full-stack development processes. He possess strong expertise in writing the technical articles and completely believes in following Agile methodology.