TypeScript vs. JavaScript: What Are the Differences?

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Rafael Timbó
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Rafael Timbó
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Chief Technology Officer
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Thinking of trying TypeScript or JavaScript, but don't know which direction to go in? Learn more about both, and why one might fit your project a little better.
Published on
February 23, 2023
Updated on
April 11, 2024

When hiring developers for your team, you're bound to come across JavaScript and TypeScript in resumes. Although many companies refer to these languages interchangeably, you shouldn't confuse them with one another. JavaScript vs. TypeScript have different use cases and capabilities.

Read on to learn more about TypeScript vs. JavaScript, their differences, and when to use TypeScript vs. JavaScript. We'll also cover TypeScript vs. JavaScript benefits and code samples.

TypeScript vs. JavaScript

At first glance, TypeScript and JavaScript are very similar. Not only are they both frequently used on the front-end, but TypeScript also builds on JavaScript. However, that doesn't mean they're the same.

What is JavaScript

Also known as JS, JavaScript is a scripting language and one of the core technologies of the internet, alongside CSS and HTML. As of 2022, 98% of websites use JavaScript for user interfaces (UI) and user experiences (UX), according to W3Tech. Additionally, all major web browsers have JavaScript engines for executing code on user machines.

Although it sounds similar to Java, JavaScript is not related to Java. In fact, they have very few similarities. For one, JavaScript is an interpreted language, while Java is a compiled language. JavaScript and Java also have different governing bodies, libraries, and runtime environments.

History of JavaScript 

JavaScript was created by American programmer Brendan Eich in 1995. It was originally called LiveScript when it first shipped as part of a Netscape Navigator beta in September 1995. However, the name was soon changed to JavaScript for the official December release. Eich considered the name change to be a marketing ploy because Java was the most popular programming language at the time.

Meanwhile, Microsoft released Internet Explorer, resulting in a browser war with Netscape. To gain the upper hand, Microsoft reverse-engineered Netscape's JavaScript to create its own version of the language, JScript. Microsoft released JScript in 1996, along with support for HTML and CSS.

In the next few years, Microsoft exploded in popularity, eclipsing Netscape. By the early 2000s, Internet Explorer was the main computer browser, which meant that JScript was now the standard for front-end scripting.

Throughout the 2000s and the 2010s, developers added more features to JScript, resulting in the JavaScript we know today. Some of the most important milestones included:

  • 2008: Google released its Google Chrome browser, which featured a speedy V8 JavaScript engine with just-in-time compilation (JIT).
  • 2009: Ryan Dahl created Node.js, an open-source, back-end, cross-platform JavaScript runtime environment that executes JavaScript code outside web browsers. Developers often use Node.js to create apps and systems.
  • 2015: ECMAScript6 was created to ensure the interoperability of webpages across various browsers. Developers use it for front-end scripting and creating server services and apps via Node.js.

How Does JavaScript Work?

JavaScript is an interpreted language, which means that it doesn't need to be compiled before runtime. Instead, browser interpreters execute JavaScript code while reading it.

Other JavaScript features include:

  • Dynamic typing
  • First-class functions, which means it treats functions like any other variable
  • Prototype-based object-orientation
  • Application programming interfaces (APIs) for working with dates, standard data structures, text, regular expressions, and the Document Object Model (DOM)

JavaScript Types

JavaScript has many built-in types, including:

Primitive Values

Primitive values are any data that aren't objects. They include:

  • Boolean: Boolean values represent values that can only be true or false.
  • Null: The Null type only has one value, "null," and represents an unknown or empty value.
  • Number: The Number type is a double-precision 64-bit binary format IEEE 754 value that can store almost any number or integer.
  • String: JavaScript's String is used to represent textual data.
  • Undefined: This is for variables that haven't been assigned a value.
  • BigInt: This numeric primitive can represent integers beyond the Number type's safe integer limit.
  • Symbol: This is an immutable and unique primitive value that can be used as the key of an Object. They are also called "atoms" in other programming languages.
Objects

In JavaScript, an object is a container for names, properties, methods, and values. You can use objects to store, manipulate, and combine values.

What Is TypeScript?

TypeScript is a superset of JavaScript that adds static typing. Essentially, it's JavaScript with optional static typing. Accordingly, JavaScript programs are valid TypeScript programs.

TypeScript History

Microsoft released TypeScript in October 2012 after two years of development. Initially, the language did not provide mature integrated development environment (IDE) support apart from Microsoft Visual Studio.

Over the next couple of years, Microsoft continued adding features to TypeScript, including:

  • Support for other IDEs and text editors, including Atom, Vim, and Webstorm
  • The ability to prevent variables from being assigned null values
  • Language additions such as spread expressions and tuples in rest parameters
  • Language features such as Variadic Tuple Types and Custom JSX Factories

How Does TypeScript Work?

Although TypeScript is based on JavaScript, it works differently.

First, TypeScript is compiled, rather than interpreted. As such, IDEs that perform background incremental compilation can catch TypeScript errors before execution.

Second, TypeScript offers better object-oriented programming and code structuring techniques than JavaScript. This means that developers will have an easier time developing readable and reusable code in TypeScript than in JavaScript.

Third, TypesScript is strongly typed, which means that it enforces typing on all data. For instance, if you set a variable as an integer, you can only interact with it as an integer type. In contrast, JavaScript is loosely typed, meaning that you can redefine variables whenever you like.

TypeScript also provides many advanced features that JavaScript lacks, including:

  • Interfaces
  • Type inference
  • Type annotations
  • Compile-time type checking
  • Namespaces
  • Tuples
  • Async/await
  • Enumerated types

TypeScript Types

TypeScript has all of the JavaScript types plus additional types. These include:

  • Any: The Any type is a way to work with existing JavaScript code. Devs can use it to gradually opt-out and opt-in of type checking during compilation.
  • Enum: Enum can be used to give more friendly names to numeric value sets. For example, you can use Enum to name a set of colors "color."
  • Void: The opposite of any, Void is the absence of any type. You will encounter "void" as the return type of functions that don't return a value.
  • Tuple: Devs can use Tuple types to express an array with a fixed number of elements with known types that may not be the same.
  • Never: This type represents the type of values that never occur. For instance, Never is the return type of an arrow function expression that never returns.
  • Type assertions: Sometimes, devs know more about a value than TypeScript does. They can use type assertions to tell the TypeScript compiler that they have already performed the necessary checks.
  • Union: Union types are created from two or more other types. An example would be String | Number, which combines String with Number.

Differences Between TypeScript and JavaScript

Here's a summary of the main differences between TypeScript and JavaScript:

TypeScript vs. JavaScript Code Example

JavaScript and TypeScript code is nearly identical. The only difference is that TypeScript code is strongly typed.

We can see this in action by comparing a JavaScript vs. TypeScript code snippet.

Let's start with a JavaScript code snippet:

let var2 = "Hello";

var2 = 20;

console.log(var2); 

Because JavaScript is loosely typed, you can redefine var2 as any variable type at any time. Executing this snippet results in 20.

Let's see how this snippet looks in TypeScript:

let var2: string = "Hello";

var2 = 20;

console.log(var2);

Executing this results in an error. This is because we assigned a number to var2 after declaring it to be a string. TypeScript's strongly typed system doesn't allow you to change variable types.

In short, if you see frequent types — such as string, boolean, any, never, and enum — before variables, you're probably looking at TypeScript. If you don't see or rarely see types before variables, you're looking at JavaScript.

When To Use JavaScript vs. TypeScript?

As you can see, JavaScript and TypeScript have many differences. As such, they have slightly different use cases.

JavaScript Use Cases

JavaScript can be used in a variety of applications, including:

  • Presenting website UI and UX: JavaScript is usually used to present UI and UX elements on sites, such as:
  • Buttons
  • Menus
  • Animations
  • Timers
  • Interactive maps
  • Dynamic content that change based on user preferences, data, and behavior
  • Building web and mobile apps: Programmers can also use JavaScript frameworks to build web and mobile apps. JavaScript frameworks are collections of JS code libraries that give coders pre-written code for app building. Popular front-end JavaScript frameworks include React, Vue, Angular, and React Native.
  • Creating web servers and applications: Developers can use JavaScript to create web servers and other back-end architecture.
  • Creating browser games: Coders can also use JavaScript to create browser games, such as RuneScape, Prodigy, and BrowserQuest.

TypeScript Use Cases

Since TypeScript is a superset of JavaScript, TypeScript can be used for any JavaScript project. It's particularly good for building and managing large-scale JS projects, such as:

  • Real-time chat applications
  • Social media platforms
  • Real-time weather apps
  • File sharing applications

TypeScript can also be a replacement for the JavaScript compiler, Babel. TypeScript can compile your project in one go, while Babel can only compile one file at a time.

Advantages of Using TypeScript vs. JavaScript

Should you use TypeScript or JavaScript for a project? The answer depends on the complexity of your project and who you have on your team.

If your project is simple and you don't have any TypeScript developers, JavaScript may be a better choice. TypeScript has a steep learning curve, even with prior JavaScript knowledge. It also has a much smaller community than JavaScript, making it harder for your devs to seek help.

However, if your project is complex and you have some TypeScript experts, consider picking TypeScript. TypeScript's static typing empowers devs to check type accuracy at build time. It can also spot and fix bugs during compilation, giving devs more time to focus on the build and deployment steps of the software development lifecycle (SDLC).

TypeScript also provides many other functionalities for web and mobile development, including:

  • Generics for creating a component that can work across a variety of types
  • Namespaces for logically grouping functionalities
  • Interfaces that tell the compiler which property names an object can have
  • Null checking for setting pointers that don't point to anything as null
  • Access modifiers for encapsulating class and member variables
  • The ability to make parameters optional

Hire TypeScript and JavaScript Experts Today

TypeScript and JavaScript are powerful front-end languages for web and mobile development. They can both be used to create stunning UI and UX for websites and apps.

However, they're not interchangeable. JavaScript is interpreted, easier to learn, and the best choice for smaller projects. Meanwhile, TypeScript is compiled, harder to learn, and best used for complex and large-scale projects.

If you're interested in hiring JavaScript and TypeScript professionals, reach out to Revelo today. We provide access to thousands of TypeScript and JavaScript programmers. All of our talent have been rigorously pre-vetted for technical and soft skills.

Need to source and hire remote software developers?

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