When I first started building websites in 2021, the decision to use JavaScript was an easy one – it was strong, well-documented, had a good community and seemed straightforward. I can recall many late nights debugging runtime errors that could’ve easily been picked up at compile-time, grappling with type coercion, and losing my mind trying to make consistent decisions in with large and growing code bases.
My transition to TypeScript was not immediate (like many Developers, I was apprehensive about adding complexity to my workflow), but after working on my first project in TypeScript, I was sold. The peace of mind that comes from compile-time error checking, the productivity booster of superior IDE support, and the self-documenting nature of typed code led me to realize that this is not just a trend, but is the future of JavaScript programming. In this blog, we would talk about typescript vs javascript and the transition from javascript to typescript.
Understanding JavaScript: The Foundation of Web Development
Javascript vs Typescript: For Small Projects
If you’re new to programming, JavaScript is an easy language to pick up: you can start developing interactive websites about two hours after your first lesson. JavaScript’s simple syntax, and the fact that it operates within a feedback loop to your browser, mean it is very forgiving when experimenting and prototyping quickly.
But the thing that amazed me the most about JavaScript in the early days was its flexibility. I remember conquering new concepts, starting with DOM manipulation and going on to perform API calls and validate forms. Then, I discovered I could also develop backends with JavaScript all thanks to Node.js! Combined with JavaScript’s event-driven functionality and asynchronous features, building responsive, real-time applications became incredibly easy.
Javascript vs Typescript: For Large Projects
As my projects become larger and more complex, JavaScript’s permissive approach began to be both a blessing and a curse. At first, I reveled in the possibility for every variable to be of any value (hello, manipulable strings!), but as I found bugs in my code, I realized how difficult it was to trace back and find where I had overlooked a simple type mismatch. This was a painful lesson that I learnt more than once as a young developer on long nights of debugging a project because when I assigned a value of a string, and my program required a number, my code crashed.
Then came the ES6 revolution! The wars were had, and finally, with features like \const/let\ declarations and template literals, and even the use of \async/await\ syntax, my JavaScript screenshot changed dramatically. My code was readable and maintainable much more easily. But despite these improvements to readability, I still found myself searching for more structure and predictability to build out larger applications.
Difference Between TypeScript and JavaScript
JavaScript’s Dynamic Typing: A Double-Edged Sword
Having spent a few years developing JavaScript applications, I have experienced the annuity of dynamic typing, both in its freedom and frustration. I vividly recall my early JavaScript projects, where I loved how quickly I could prototype features without any concern of type declaration. If I needed a variable to store a user ID, I would just declare it and immediately begin to use it. If I wanted to store a few arrays with multiple types, it was no problem either for JavaScript to deal with.
The felxibility of the language allowed me to develop applications quickly and also incited creative solutions to problems. There is a particular moment in my programming career I will not forget when I developed my first interactive calculator. It felt so incredible that users could provide input to the program without converting data types – it felt "magical." It was the implicit type coercion of JavaScript that automatically converted strings to numbers so the calculator could perform the calculations for the user – the math function felt intuitive.
Javascript For Large Applications
As the applications I developed became larger and more complex, the same flexibility became a petri dish of all sorts of bugs. I remember spending three hours debugging a feature that simply was not working, only to find that the function was getting a string instead of a number. And the polymorphism was so deep in the application logic that it was nearly impossible to go back and pinpoint the equations where the error originated.
The infamous "undefined is not a function" error became my nemesis in my early hours of a purely JavaScript career. These runtime surprises certainly forced me to code in a more defensive manner, but they also highlighted the need for better tools to hit these types multiple issues prior to deploying.
Benefits of Static Typing: Lessons from the Field
I became very aware of how lovely static typing was from my painful experiences with JavaScript’s dynamic typing. What I learned was that static typing changes the development experience by moving error detection from runtime, where there is no choice for refactoring, hacking, or changing at all, to compile-time where the compiler will error. This is a great time-saver since it happens at compile time rather than debug time or run time – I can imagine that I’ve saved weeks through JavaScript’s quirky errors.
If I declare that a variable is a number from the beginning, the TypeScript type system is enforcing that the type stays unchanged throughout the application. This may seem unrelaistc at first, especially coming from JavaScript’s anything goes approach, but is liberating. This type enforcement also means when refactoring the code I can have the compiler check and validate that nothing has broken due to some type problem.
The early error detection factor cannot be overstated, hiding in this simple blessing is an important shift in the developers’ workflow. I much rather have type mismatches happen in my IDE with an error message that clearly outlines what went wrong, rather than happening in production (where worse case the end users discover it) or read someone’s email alongside their message stating what they did and why it does not work. I am also totally fine with having automated code coverage (because it can) because discovering errors sooner is ultimately better than reactive debugging, and I now see the change to proactively detect issues before producing code, which has changed the way I think about writing software moving forwards.
TypeScript: Bringing Static Typing to JavaScript
TypeScript bridges the gap between the flexibility of JavaScript and the benefits of a statically typed language. When looking at typescript vs javascript capabilities, TypeScript has a sophisticated type system that allows more ability to infer types automatically, while giving us the ability to annotate types explicitly, on demand.
The distinction between typescript and js becomes even more clear when we bring in .tsx files. What is a .tsx file? It’s a ts file that has JSX inside of it. When working with React, we still get the type safety with React components, but we also can use the same JSX syntax as JavaScript.
The TypeScript compiler does an exhaustive analysis of code before you run your file. The compiler does type checks for compatibility or will flag any things don’t compile. The typescript vs javascript difference eliminates many common pitfalls of JavaScript with it’s compile time checking.
Static Type Checking
TypeScript static type checking extends beyond just type namings. Null safety, exhaustive switch checks, and there is advanced type inference that is able to recognize complex relationships of object properties as well as function signatures.
The compiler is capable of identifying that you are trying to access a property that may not exist or calling methods on undefined values, or sending the wrong types to a function – a complete checking system like this makes it so the chance of runtime errors is small.
Advanced TypeScript Features: Beyond Basic Typing
Leaning of TypeScript has allowed me to discover that there is so much more than typing in types. Advanced features, like conditional types, mapped types, and template literal types, have provided another layer of sophistication to the way I conceptualize complex application architecture when building them.
Generics and Utility Types
Generics allow you to be able to write reusable code with multiple types while providing type safety. The first time I was able to successfully create a generic API response handler was when I felt like I had made it to the next level of being a developer.
typescript
interface APIResponse<T> {
data: T;
status: number;
message: string;
}
function processResponse<T>(response: APIResponse<T>): T {
if (response.status === 200) {
return response.data;
}
throw new Error(response.message);
}Utility Types, such as Partial<T>, Pick<K, T>, and Omit<K, T> have become essential in my day-to-day development. They allow you to create advanced type transformations that are impossible in plain JavaScript.
Union Types and Type Guards
Union types and type guards have completely eliminated whole classes of bugs for me in my applications. The flexibility to define that a parameter can either be a string or number and then employ type guards to process different cases is both flexible and safe.
typescript
type ID = string | number;
function processID(id: ID): string {
if (typeof id === 'string') {
return id.toUpperCase();
}
return id.toString();
}Performance Considerations: TypeScript vs JavaScript Runtime
One of the misconceptions I’ve encountered is that TypeScript is slower than JavaScript. However, the performance difference between typescript vs javascript is almost negligible at runtime, because typescript transpiles into javascript. While the compilation process adds development time, it does not affect performance.
What TypeScript provides is better opportunities for optimization. The type information allows bundlers and minifiers to be much more aggressive in their optimizations, and thus, at times, your production builds will be smaller and faster.
Personally, I have found that any overhead to development time is far outweighed by the performance I gain. All the time saved by debugging and increased developer velocity more than compensates for a build step.
TypeScript Object Types
Unlike objects in JavaScript which provide more generalized control, objects in TypeScript give you really precise control over data structures, once again showings a typescript vs javascript difference. You can define exact shapes, optional properties, readonly fields, as well as conditional types based on other parameters.
All of these latter more advanced type controls make it possible for you to model complex business logic directly in the type system – regardless if you are using standard .ts files or .tsx files.
Team Collaboration and Enterprise Development
The greatest benefit I’ve seen with type adoption is better communication within a development team. I’ve been in numerous development teams and sized and TypeScript has served like a communication medium between developers. When interfaces and core data objects and types are declared explicitly, there is no ambiguity regarding the data structure or what (or could) be the API contract.
The self-documenting nature of TypeScript has also transferred well into enterprise type environments. When you onboard new team members it proved useful to help them ramped up quickly, in addition to implicit knowledge transfer when the code itself serves as a visual documentation of its intent, no matter how complex.
Less time lost in code reviews mitigates time lost for developers so to have the TypeScript compiler do the "grudge" work of ensuring that types match makes human communication during a code review, thus adds more value.
Testing and Quality Assurance
TypeScript has changed the way I think about testing and quality assurance. Although TypeScript does not eliminate testing completely, it greatly reduces the number of unit tests required to cover the basic safety scenarios testing of basic types.
When I used to code in JavaScript, I often created tests just to validate that my functions correctly handled unknown types of input. In the TypeScript world, many of these tests no longer need to exist – the TypeScript compiler verifies that the functions may only receive appropriately typed arguments.
This change allows test time to be spent on tests related to business logic and edge cases, or integration scenarios as opposed to validating types of input. The end result is more meaningful tests with better coverage related to actual behavior of the application.
Industry Adoption and Market Trends
Having watched the industry closely since 2021, I have witnessed TypeScript drive a meteoric rise in professional development environments. TypeScript has grown from a Microsoft brand product into a de facto standard for serious JavaScript development.
When looking at the npm system, this new industry standard is reflected in how most of the common libraries are defaulting to ship with TypeScript definitions. This further develops a positive feedback loop, making TypeScript a more attractive option to take on new projects and more manageable for existing projects.
Common Misconceptions and Myths
During my TypeScript path, I’ve met many types of misunderstandings keeping developers from moving ahead. I’ll run through the most popular ones based upon real-world experience:
"TypeScript is too much for small projects" – I thought this too at first, then I realized that every project, no matter how small, gets value from any amount of basic type safety. You don’t have to use all of the advanced features right away. A little type annotation gives value right away.
"TypeScript slows down development" – There is a learning curve to start, but I feel once you get it, TypeScript speeds up your development time. The IDE support is so helpful, and the errors you can catch at compile time more than make up for (usually) a small amount of additional typing.
"TypeScript is a passing fad" – given Microsoft’s backing, its growing adoption by the industry, and the very real problems it solves, I think TypeScript is here to stay. If you put in the time to learn TypeScript, you’ll get a return on your investment in the long-run.
JavaScript Advantages: When Simplicity Wins
Even with my excitement for TypeScript, JavaScript has many advantages for very specific use-cases that I run into often. Obviously, a straight-forward language like JavaScript has value in that you can get going quickly and easily from just learning how to build applications without having to learn a type system that is complicated.
The enormous ecosystem of JavaScript libraries and frameworks keeps solving almost anything a developer could need. Browser compatibility is immediate since JavaScript runs natively without compilation steps, making it perfect for quick experiments and proof-of-concepts.
For small projects, personal scripts, and some one-off tools, JavaScript has a low setup barrier which makes it the preferred choice. I still use vanilla JavaScript for many things like some simple automation scripts, or just to play around with a quick idea.
The dynamic nature of the language creates very powerful metaprogramming options that can be hard to navigate when using TypeScript. Even if I rarely utilize it, metaprogramming options provide some very special flexibility that makes using vanilla JavaScript appealing to imaginative developers.
Framework-Specific Considerations
In working with many frameworks, I have seen some interesting ideas referenced in the typescript vs javascript story.
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React Development
I am generally working in React and Nextjs with TypeScript now. .tsx files and React provide a delightful development experience with props validation, component interfaces and hook typing. New developers who are not familiar with React and TypeScript might experience some steep learning curve.
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Vue.js Experience
Vue’s gradual TypeScript adoption has been impressive to follow. Vue 3’s composition API works beautifully with TypeScript, providing type inference that feels almost magical after years of prop-types validation in JavaScript.
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Node.js Backend Development
Server-side TypeScript development has proven particularly valuable in my projects. The ability to share types between frontend and backend, combined with excellent Express.js TypeScript support, creates a cohesive development experience.
When Should You Use TypeScript?
As a developer with experience with TypeScript and JavaScript, I’ve gained an understanding of when to choose one over the other, which is vital for the success of your project. TypeScript works great for enterprise applications, large teams, and projects that will require maintenance for the long term. The typescript vs javascript comparison shows TypeScript coming out on top with complex applications where more than one developer is contributing.
One key takeaway from my experience is using TypeScript when there is a requirement for code reliability, especially for software such as financial systems, healthcare apps, or any application where the bug can have major consequences. TypeScript works well for libraries and frameworks that other developers will be consuming, especially when the library is a React component library and the language is .tsx.
Also, if your team is a mix of experienced and inexperienced developers, using TypeScript is an option. The type system acts as guardrails to inculcate good habits into junior developers from common pitfalls, while at the same time helping senior developers express complex patterns more readily.
When to Stick with JavaScript
Regardless of my enthusiastic disposition toward TypeScript, there are certainly circumstances, based on my own practical experience, where JavaScript is still the better choice.
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For rapid prototyping and proof-of-concepts, JavaScript is impossible to beat given execution time, overhead, and the speed at which you can get up and running.
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When it comes to educational projects and learning exercises, JavaScript’s low barrier to entry can certainly help. I also consider that when introducing programming concepts, types can be an extra burden. If the learner is focusing on logic and problem solving, types might distract from the goal.
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If you have a legacy codebase in JavaScript with lots of it, and it is functionally ok, then it might be cumbersome to justify the effort to migrate. If the team is very experienced with JavaScript patterns and has a routine for thinking about code quality and they are diligent, the return on the overhead from the transition might not be worth it.
-
Small utility scripts, build tools, and automation that are quick to build and not likely to be supported long-term are prime candidates for JavaScript.
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Time constrained projects with teams that are unfamiliar with TypeScript should be mostly successful with JavaScript given they won’t encounter the delays from a learning curve while trying to get a project completed.
The Future of JavaScript and TypeScript
The Future Of Javascript:
From a developer’s perspective, I find many of the evolutionary trajectories of JavaScript and TypeScript really exciting. In the future, we will probably continue to see JavaScript specifications borrow from TypeScript. TypeScript will probably continue to help bring TypeScript into the larger scope of the developer ecosystem.
The new features introduced with JavaScript, such as optional chaining, nullish coalescing, and even pattern matching, start getting rid of some of the pain points and issues with JavaScript that led many developers to TypeScript in the first place. But these new features do not detract from the primary value proposition of TypeScript: compile-time type checking.
The Future Of Typescript:
The TypeScript dev team is actively working on better performance, inference, and support for modern JavaScript features as shown in their official roadmap. They are also continuing to work on compatibility with JavaScript as much as possible to provide a clear and easier path for new adopters from the JavaScript ecosystem to TypeScript.
From where I sit in my corner of the industry, I believe TypeScript adoption will continue to explode in developer workflows, especially in enterprise and even open-source development. The network effects of increased adoption create a virtuous cycle of benefits are extended not only to projects where TypeScript is being used, but to all developers in the ecosystem.
Tooling and Development Environment
The tooling ecosystem today for both languages is also much more advanced than it was when I took the plunge. Modern tooling, especially editors like VS Code, provide an enjoyable experience for people developing in either JavaScript or TypeScript. This advantage is magnified in complexity of the project.
IDE Support and Developer Experience
The contrast in IDE support for js vs ts is remarkable. Typescript can provide all of the features mentioned above (that are impossible in dynamic javascript) because it provides static analysis of code that leads to precise autocomplete, safe refactoring, and smart code navigation.
In my experience, I also find debugging TypeScript applications easier, thanks to deeper semantics with the language that leads to better error messages, and its support for source maps. Typescript also lets the compiler catch many of the issues that require runtime debugging sessions in JavaScript.
Build Tools and Workflows
In addition, modern build tools, including Vite, esbuild, and SWC, let you work almost as quickly with Typescript as you can with JavaScript, with build times fast enough that you’d still have an immediate types-in-the-context-of-js experience while building, despite a type check step.
With a variety of popular bundlers, and first-party support from cloud platforms, initial setup for a Typescript project has become almost identical to a JavaScript project, with nearly no additional configuration required for Typescript (aside from installing types).
The Shortcomings of JavaScript
JavaScript’s number one problem is its permissiveness. This permissiveness allows quiet errors (that we can’t see) to silently ‘walk up’ throughout an application. Also, type coercion means that types can cause unintended results and errant functional behavior. There’s no compile-time errors for developers, meaning that any real-time errors tend to be produced in production too!
Developers coming from traditional programming environments often struggle with prototype-based inheritance, scope, and the many possibilities of async programming patterns.
The rapid changes in JavaScript, while typically beneficial, can sometimes lead to compatibility issues among libraries as well as the need for developers to keep continuously updating their development practices to align with best practices.
TypeScript Makes JavaScript Better
TypeScript is a superset of JavaScript, which is to say you can use TypeScript without any changes to JavaScript. TypeScript goes a long way toward adding static typing and the bonus safety and tooling features that static typing offers, while still letting a developer express themselves in the flexible and dynamic nature of JavaScript that they know and love.
The follow-on benefit of its adoption path is that it is incremental; you can add TypeScript to your toolkit gradually, reaping its benefits quickly, and learning advanced features of TypeScript down the road. You adopt TypeScript while minimizing risk, and your team will adapt develop at their own pace.
TypeScript is having an impact on JavaScript development practice beyond just TypeScript projects. It is also causing developers to consider higher-level abstractions available within their own JavaScript projects, in order to improve the code. These good habits will benefit any JavaScript coding project regardless of its abstraction.
Learning Curve and Training
How quickly you pick up TypeScript is going to depend on your background with JavaScript and with statically-typed languages. Developers with backgrounds in Java or C# often have an easier time picking up TypeScript than someone with solely a JavaScript background because the primacy of type thinking is often so alien to them.
At first, most teams will find that the newness of TypeScript leads to a slowdown in development while they are getting used to new concepts and tooling changes. And this slowdown is understandable given their prior experiences. But fortunately, over the exercise of using TypeScript and the benefits it brings, you will enjoy the outcome of increased code quality and less time spent debugging.
How to Migrate Your Existing JavaScript Project to TypeScript
Knowing the best way to transition workflows from TypeScript to JavaScript in reverse – moving from JavaScript to TypeScript – takes a little planning. Start with installing TypeScript and create a tsconfig.json file with easy settings for your team to turn on and off at their discretion without overwhelming errors.
Next, transition the files, starting with individual leaf modules that ultimately depend on the fewest number of files. If your team is using React, consider transitioning .jsx into .tsx files to leverage all of the JSDoc type checking that comes with TypeScript for your JSX components.
Quick tip: You can mix JavaScript and TypeScript files with the allowJs compiler option, using it as a transition step, effectively introducing TypeScript incrementally without breaking existing code! This method allows teams to slowly discover how to work with typescript vs javascript without interruption to productivity.
Debugging TypeScript
TypeScript debugging gives your team source maps that allow for a link between your compiled javascript and original Typescript. Establishing a development environment with adequate debugging functions is important for effective developer experiences, especially no matter if you are a Tier 1 or Tier 2 BI Reporting by Product lines. Developers, want access to standard debugging features found in most up-to-date software development environments: set breakpoints, view variables, inspect the call stack, etc..
In general, the TypeScript compiler describes clearer error messages with location of code with proposed fixes in some cases, compared to JavaScript Runtime errors. IDE integration gives a means of displaying errors in real time, and sometimes suggest the next things to do, and/or even quick fixes.
TypeScript’s Relation to JavaScript
TypeScript as a superset of javascript has built-in user transitions and gives you as the developer an explicit migration strategy when moving to TypeScript, so you can still benefit from your JavaScript libraries and knowledge. All valid JavaScript is also valid TypeScript.
The TypeScript team follows JavaScript in a 1-1 fashion which means they often have new features of JavaScript ready to use before they become recommendations with the spec, and therefore you can use new features of the language while having broad compatibility with what is being supported on the browsers.
TypeScript compiles to readable JavaScript which allows us to know what our output looks like and to easily debug our code. TypeScript can target multiple versions of JavaScript, after our code has been properly designed and tested against a specific version we can be confident it will save us development time to switch targets and know we will work across all intended runtime environments.
Pros and Cons of TypeScript and JavaScript
TypeScript Pros: The IDE support is the best, compiler errors before running code, better refactoring tools, self-documeting code, great for large teams and complex applications.
TypeScript Cons: Extra compilation step, learning curve in concepts to grasp, notationally verbose syntax in places (note it’s better), the potential to over engineer both simple solutions.
JavaScript Pros: Easy to work with, immediate feedback from running reveals output, simple syntax for developers to learn, large ecosystem for libraries that you aren’t not using, better on board for new developers, great for rapid prototyping, no build process.
JavaScript Cons: – Runtime errors, limited IDE help, hard to refactor, type bugs, difficult to maintain in large codebases.
TypeScript vs JavaScript: Use Cases
When considering all the js vs ts differences, there are clearly unique use cases for each language. TypeScript is best for large enterprise applications, API development, component libraries, and pretty much anything where type reliable code is vital. The distinctions between typescript and javascript become more apparent when working on large applications.
JavaScript is best for using quick scripts, creating a simple website, educational purposes, and wherever speed of development is more important that taking into account the maintenance of the code for the long haul. Understanding when to create .tsx files or ".js" files revolves around if you are creating React components that can benefit from the trust and safety of types.
The questions around typescript vs javascript can be reasonably straightforward so consider the example scenarios: Use TypeScript when they are will involve large applications with complex business logic, multiple development teams, or if there is a requirement for extensive testing & documentation. Use JavaScript when there is a process of rapid prototyping or working in a development team of people new to the concept of static typing.
For more practical examples and advanced techniques, explore our comprehensive guides on TypeScript implementation, installation procedures, and testing coverage optimization.
Conclusion: Making the Right Choice for Your Development Journey
After years of using both JavaScript and TypeScript, my view changed from seeing them as competing technologies to complementary technologies in the developer’s toolbox. The question of which one to use is not which one is better in general but rather which one helps you most effectively with your specific use case, team, and project.
The JavaScript vs TypeScript debate is probably going to continue. Both JavaScript and TypeScript have already taken hold in the modern development world. JavaScript will always exist as the foundation of web development, whereas TypeScript has become the de facto option for large scale, professional applications.
In the end, being proficient in both JavaScript and TypeScript will make you a more well-rounded developer. As a developer, the more tools you can master, the better off you will be. Being able to tell when to use which tool, as well as how to transition between them, and use their unique advantages will serve you well for the entirety of your development career.
Frequently Asked Questions
What is the main difference between JavaScript and TypeScript?
The overriding difference between languages is their typing systems. JavaScript is a dynamically typed language, which means all kinds of types are checked at runtime, while TypeScript is a language that adds static typing on top of JavaScript with its own compile-time error checking. Code in TypeScript is essentially written in JavaScript and simply has more type safety and newer language characteristics.
Is TypeScript faster than JavaScript?
There isn’t an inherent difference of speed when it comes to runtime because TypeScript compiles to JavaScript. However, the compiler in TypeScript means that you can create more optimized code and catch many errors at the editing step versus the runtime step meaning better reliability and potentially faster application performance.
Should I learn JavaScript or TypeScript first?
A beginner should learn JavaScript first so that they can learn core programming concepts before taking on the extra complexity of type systems. Most people do not need static typing functions when first learning a programming language, and it is often easier to understand and gradually master JavaScript alone. Once you understand the basic principles of programming with JavaScript, learning TypeScript will be much easier and is also more meaningful.
Is TypeScript adopted by large tech companies?
Microsoft, Google, Facebook, Netflix, Airbnb, Spotify, Slack and more companies are all using TypeScript in a huge way. Countless startups and large organizations are also now using TypeScript to make code easier to maintain and for increased developer productivity.
How hard is migrating from JavaScript to TypeScript?
The difficulty of migration depends on the size and structure of your project. You will find TypeScript’s gradual adoption makes the migration much more practical – you can convert your files one at a time, and you can always use JavaScript libraries even tern with types. Most teams find the transition easier than expected.
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