TypeScript vs JavaScript: Learn The Difference

If you're considering taking up web application development as a career, or even as a serious hobby, the question will arise, what language should you invest your time and efforts in. Your goal is to maximize the value of your applications and to improve your marketability.

JavaScript has long been a favorite in the world of developers, and there is plenty of room in the market for new talent to create and maintain JavaScript applications. But more recently, TypeScript has grown in popularity, even transforming seasoned JavaScript programmers into TypeScript aficionados.

TypeScript vs JavaScript: What Is TypeScript?

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Most developers are quite familiar with JavaScript and its many advantages over alternative languages for developing web applications:

  • Easy to learn and become productive
  • Popularity: wide community of developers with which to share experiences and problems
  • Flexibility: works well in concert with other languages
  • Efficient: client-side operability reduces demand on server
  • Frequent updates: JavaScript is being enhanced and updated on a regular basis ? ECMA Script updates (ES5 and ES6) continue to update browser support within the standards for JavaScript, extending the compatibility and functionality of JavaScript

But even with the many advantages and tools offered by JavaScript, TypeScript entered the development picture with new technology that takes your coding activity to the next level.

TypeScript contains all the functionality that made JavaScript so popular and useful for web development. As a "superset" of JavaScript, your JavaScript code will run unmodified in TypeScript. TypeScript programs actually compile into JavaScript code.

Where Did TypeScript Come from and Why?

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Microsoft introduced TypeScript in 2012, intending to give developers an improved programming language that includes advanced features and options:

  • Type annotations
  • Static type checking
  • Increased development productivity
  • Full JavaScript features, with enhancements
  • Type management ? JavaScript does not specify data types for variables? TypeScript allows you to specify the data type for your variables (primitive or object)

From a background standpoint, it's worth noting that Microsoft?s underlying purpose for creating TypeScript was to speed up development by their own internal teams who were struggling to build JavaScript applications for internal projects.

Interestingly, TypeScript itself is actually written in TypeScript.

Why Use JavaScript and TypeScript (or Both)?

There are many reasons to select JavaScript as a development language, as borne out by the millions of software developers worldwide. Stack Overflow estimates there are 20 million application developers on Earth, with the most popular language by far being JavaScript. But with the advent of TypeScript, even the most experienced JavaScript programmers are taking to this technology due to the advantages of TypeScript vs. JavaScript.

JavaScript Advantages

JavaScript has offered software engineers many features and options for years, proliferating its use for many reasons:

  • Ease of use: JavaScript is one of the simplest languages to learn and become proficient in.
  • Speed: it can be run immediately on the client side ? even without compiling. Client browsers can interpret and run JavaScript without transformation, unless outside resources are needed.
  • Extensive community: being one of the most popular languages on the planet for web development, there are countless examples of coding, numerous user forums, YouTube tutorials, and of course texts published to help you get started, and to develop your programming skills.
  • Add-ons: when you need special functionality, chances are that others have run into the same or similar situations, and there is an abundance of third-party tools and add-ons that help you with those requirements.
  • Functionality: developers can create fully functional web apps front to back with JavaScript.
  • Current: with such a population of developers, ECMA International is committed to releasing enhanced support and functionality to JavaScript standards.

TypeScript Advantages

TypeScript has now come along offering many additional features:

  • Static type checking: as you key a JavaScript program you specify variables, but the type is not defined until you assign a value to it when you run the program. This can mean that a variable may wind up with an unintended type, which could cause application issues later in the program, or when used by additional program functions. With TypeScript, you can optionally define the type of your variables as you key, making the decision yourself on what the data type will be. When the generated JavaScript code is executed, any unexpected values will still be accommodated, with a notification that the results are questionable, but will not abort the program.
  • The static type checking feature will catch issues with your code right as you type. That doesn't mean your code will be bug-free, but it does give you a sort of programming ?spell-check? to detect issues before you ever begin to test.
  • Class use: with the release of standard ES6 by ECMAScript 2015, JavaScript now provides the ability to use classes within your programs. But TypeScript already supported the use of classes by permitting the extension of existing classes, and by allowing you to utilize inheritance to construct new classes.

TypeScript vs JavaScript: When and How to Use Each of Them

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Essentially, since TypeScript produces JavaScript, it seems logical that you should take advantage of the additional features of TypeScript to speed code generation and increase your development productivity.

That may not always be the case.

When to Use TypeScript

There are plenty of good reasons and situations that warrant developing with TypeScript:

  • As Microsoft learned in creating TypeScript, development teams working together can benefit from using the language. Large development efforts can be broken up into smaller segments, allowing individual programmers to work on specific APIs or interfaces that work together with other programs to produce a complex application. This can improve productivity and reduce project costs by assigning less complex functions to new or junior-level programmers, while seasoned veterans can tackle the more business-critical or challenging functionality.
  • Static typing speeds up program creation and highlights obvious bugs as you type, saving time in finding errors when debugging and testing applications.
  • TypeScript generates clean, optimized JavaScript code.

When Not to Use TypeScript

Since TypeScript creates JavaScript code, you may think (as many developers do) that there is no reason to avoid it ? using TypeScript would be a "can't lose" situation. But that's not necessarily the case.

There are reasons and scenarios that could make the use of TypeScript less than optimal:

  • Since TypeScript permits the specification of variable types, developers may proceed under the illusion that they are safe from mismatched data types. That may be overstated, remember that compiling your TypeScript code results in a JavaScript program, so when you access data from other sources to populate your variables, you don't have control of the data fed to your program from the server side. This can cause confusion especially for newer TypeScript developers who think they are shielded from JavaScript type limitations, and don't test or validate data types at runtime.
  • TypeScript developers still need a comprehensive understanding of JavaScript. You cannot train or hire a TypeScript-only developer and expect bug-free applications without a background in JavaScript. That means you have a learning curve for TypeScript development. If your development project does not allow for the time and expense of training and the learning curve, TypeScript is likely not your best option.
  • If you have a large investment in JavaScript applications, it may not make sense to try and retrofit a massive amount of JavaScript code under TypeScript.
  • TypeScript requires the extra step of compiling to create the JavaScript programs, where JavaScript programs run in the client browser without compiling.
  • TypeScript is relatively new, and has nowhere near the base of developers, libraries, forums, and training courses available that are enjoyed by the JavaScript community. There are those who remain skeptical of future enhancements or support for TypeScript, at least compared to JavaScript.

TypeScript vs JavaScript? Making the Choice

Choosing between TypeScript and JavaScript depends on several factors:

  • Do you have a large development project with multiple developers engaged?
  • Is there time for training in TypeScript, or are experienced programmers available?
  • Are you looking for the most productivity from your programming staff?

If the answer to those questions is a resounding yes. TypeScript is your best solution.

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On the other hand:

  • Is there a significant investment in JavaScript programs in your application portfolio?
  • Do your programmers have extensive JavaScript experience, and a lack of interest in TypeScript?

If yes is your answer to those questions, it may be more beneficial to stick with JavaScript.

To be sure, many businesses and third-party software developers have embraced TypeScript for application development, and the community is growing. More tools are hitting the market that enhance the TypeScript language as a complete framework for building applications.

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