TypeScript vs JavaScript: Which Should You Learn and When Should You Use Each?

What Is TypeScript?

TypeScript is an advanced programming language that was created by Microsoft in 2012 and is led by Anders Hejlsberg. It is a superset of the JavaScript programming language. It helps the developer to detect errors in the code at coding time rather than runtime.

Browsers do not support TypeScript. You create the .ts file, and then it gets compiled to JavaScript by the TypeScript Compiler.

TypeScript provides a type-checking facility in the JavaScript programs. Simply define the types of your variables, function arguments, or return type of functions and TypeScript will verify whether your code follows this type or not.

Key Features of TypeScript

• Static typing: You tell the compiler what a particular value is supposed to be a number, a string, or something else and the compiler ensures that you adhere to it.
• Type inference: TypeScript infers the majority of the types for you based on your values.
• Interfaces and type aliases: They represent the structure of objects and API responses.
• Generics: Write one function that will work safely with multiple types.
• Enums and union types: They limit a particular value to some finite options.
• Editor support: You get better code completion, rename and go-to definition with type information.
• Modern syntax: Write modern ECMAScript and compile it down to an old target.

Imagine that your type system is a sort of logic spellchecker. It will not write the code for you.

Also read: 52+ Top TypeScript Interview Questions and Answers for All Skill Levels

What Is the Difference Between TypeScript vs JavaScript?

The short answer is that JavaScript checks your code when it runs, and TypeScript checks it before. 

Here are the typescript vs javascript differences:

TypeScript vs JavaScript Syntax With Examples

A good typescript vs javascript code example starts with a simple mistake. Here's a function that adds two numbers in JavaScript.

function add(a, b) {
  return a + b;
}

add(5, "10"); // "510"

No error. You get the string "510" and a bug that surfaces three screens later. The same function in TypeScript looks like this.

function add(a: number, b: number): number {
  return a + b;
}

add(5, "10"); // Error: Argument of type 'string' is not assignable to parameter of type 'number'

The editor underlines the call right away. You fix it before saving the file.

Objects get the same treatment. An interface describes the shape once, and every function that uses it gets checked.

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

function greet(user: User) {
  return `Hello, ${user.name}`;
}

The question mark means email is optional. Pass an object without a name and TypeScript stops you.

Also read: What are the 4 Types of Programming Languages?

What Are the Similarities Between TypeScript and JavaScript?

TypeScript does not override JavaScript, rather, it works based on it. This is the reason why there is so much similarity between the two languages.

Both JavaScript and TypeScript share the same basic elements.

• Same syntax for variables, loops, functions, and classes.
• Same runtime behavior because TypeScript is compiled into JavaScript.
• Same ecosystem comprising npm, Node.js, and all the frameworks.
• Same asynchronous behavior using Promises and async/await.
• Same environments in which to execute, such as browsers, servers, and serverless functions.

If you know JavaScript, you already know about 80 percent of TypeScript. The rest is learning how to describe your data. 

The frameworks are very similar to each other. All React, Vue, and Svelte projects begin in any language through the official templates. Angular and NestJS take it even further as they are written in TypeScript. Express, Fastify, and all testing tools handle both of them with no additional configuration.

They are also very similar in terms of tooling practices. ESLint, Prettier, Jest, Vitest, and Git all behave the same way in both languages. The workflow of your team is barely impacted by the type system.

Must read: What is Syntax and Parsing in NLP?

When Should You Use TypeScript vs JavaScript?

As we got to know from previous sections about the differences and the similarities of TypeScript vs JavaScript. We should also know when to use TypeScript vs JavaScript:

If you notice, you’ll see that none of this is absolute. A solo developer on a five-year project may want to use TypeScript from day one. A large team shipping a short campaign page may not bother.

Use JavaScript when speed matters more than structure. Think browser extensions, automation scripts, small widgets or a weekend prototype you might throw away.

Use TypeScript when mistakes cost money. Think checkout flows, dashboards, shared component libraries and APIs that other teams depend on. If new developers join every few months, types also save hours of "what does this function expect?" questions.

Which Should You Learn First?

Learn JavaScript first. 

TypeScript assumes you already understand functions, objects, arrays, scope and async code. Without that base, the error messages feel like another language. Invest some time in JavaScript for a few weeks, build one small project, then add types. 

There's a job angle too. Many front end and Node.js job listings now ask for TypeScript, so it's worth learning soon after the basics. You won't lose time. Everything you learn in JavaScript carries straight over.

Also read: Top 15 Front End Frameworks

What Are the Advantages and Disadvantages of TypeScript and JavaScript?

Neither of the two languages is perfect for all cases. Each of them sacrifices something in exchange for something. 

Here are the advantages and the disadvantages of TypeScript and JavaScript:

Conclusion

The selection between TypeScript vs JavaScript programming languages depends on the programmer's web development objectives. 

JavaScript programming language is a client-side programming language, which means that the processing of the program takes place in the browser and not in the server. 

Client side and Server Side Programming Languages can be compared with front-end vs back-end programming languages. It revolves around whether the program is processed on an individual device called a "client."

If you are a beginner at programming, then your first choice would be JavaScript. When you master variables, functions, objects, and asynchronous programming concepts, then it becomes easier to learn TypeScript.

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