Top 8 JavaScript Testing Frameworks: Everything You Need to Know

JavaScript has been powering web development since the early 2000s. A mainstay of interactive web development, JavaScript has been the recipient of many language enhancements over the years. One such enhancement is TypeScript.

TypeScript is an open-source programming language that was developed at Microsoft in 2012. The intent behind its introduction was to handle large-scale development projects better than JavaScript. It slowly gained favor with developers and in May 2022 joined the top five most wanted programming languages.

As a web developer or a hiring manager for a new development project, you are likely to come across the JavaScript vs TypeScript dilemma. Read on to learn more about the differences between the two and which one is the better choice for your project. 

What Is TypeScript?

TypeScript is an open-source, object-oriented programming language syntactical with JavaScript. This means that TypeScript shares its syntax and libraries with JavaScipt. In essence, it’s simply a superset of JavaScript, used to write clear JavaScript code.

TypeScript brought features like optional static typing, classes, and interfaces. It can be executed on Node.js or any browser supporting ECMAScript 3 or newer. With its explicit type system and pre-compilation debugging, TypeScript is ‘JavaScript that scales’.

Who Is Using TypeScript?

TypeScript is used by web developers who need a more scalable language for large-scale projects. Companies like Microsoft, Accenture, Slack, AMD, and more currently use TypeScript for many of their projects.

What Are the Advantages of TypeScript?

TypeScript was created as a means to improve JavaScript’s capabilities. It brings several key advantages over JavaScript that make it ideal for many modern development projects.

1. Static Typing: TypeScript enforces the declaration of variables with a type. This is in contrast to JavaScript, which being loosely typed, allows redefining variables at any time. Static typing ensures bugs can be detected early, increasing productivity and reducing troubleshooting time. 
2. Early Error Detection: TypeScript points out compilation errors in the pre-compilations stage, unlike JavaScript which is an interpreted language and detects errors during runtime. Hence, TypeScript reduces the likelihood of getting runtime errors. 
3. Enhanced JavaScript: TypeScript is essentially JavaScript on steroids. It not only enjoys all of JavaScript’s features like inheritance, encapsulation, and cross-browser compatibility but also builds over them. It supports ES6 features like compact codeset, modules, arrow functions, and more. 

What Are the Disadvantages of TypeScript?

TypeScript also has a few disadvantages as compared to JavaScript.

1. Compilation: TypeScript is a transpiler and needs to translate its code into JavaScript code. Due to the additional step of compilation of .ts files to .js files, TypeScript code takes longer to run, as compared to that of JavaScript. 
2. Steep Learning Curve: TypeScript requires a steeper learning curve than JavaScript. It requires scripting knowledge and learning JavaScript as a precursor. 
3. Strongly Typed: Due to its nature, TypeScript can sometimes feel rigid and labor-intensive, unlike JavaScript which allows more flexibility for the developer. 

What Is JavaScript?

JavaScript is one of the most widely used programming languages to develop interactive web pages. Created by Brendan Eich in 1995, JavaScript follows the rules of client-side programming and can be used seamlessly with technologies like REST APIs, XML, and more.

JavaScript still ranks in the top five most wanted programming languages, according to the Stack Overflow Developer Survey 2022. It’s a lightweight language that provides a unified development environment and integrates well with many other frameworks.

Who Is Using JavaScript?

JavaScript is an open-source web development language used virtually by every entity on the web. It’s compatible with every browser, works great for small scripts, and allows cross-compilation. Companies like Meta, Reddit, Asana, Slack, eBay, Telegram, and more use JavaScript for the majority of their projects.

 

What Are the Advantages of JavaScript?

JavaScript predates TypeScript by around 15 years and enjoys quite a few advantages over its newer variant.

1. Framework Support: JavaScript has support for many more frameworks when compared to TypeScript. Its vast collection of frameworks and libraries can make the development process more streamlined for developers.
2. Community Support: Due to its longer existence and sustained popularity, JavaScript’s community is much more robust and mature when compared to that of TypeScript.
3. Unified Development: Though JavaScript was initially targeted toward front-end development, its latest versions have added support for back-end development as well. 

What Are the Disadvantages of JavaScript?

JavaScript is prone to the following disadvantages when it comes to debugging and browser support:

1. Browser Support: JavaScript, in many cases, outputs different results in different browsers. This increases the chances of various functions not being supported by one browser or the other.
2. Delayed Error Detection: JavaScript’s error detection is slower and delayed as compared to that of TypeScript. Even a single error can halt a code’s execution. 

What Are the Main Differences Between TypeScript and JavaScript?

After learning about the pros and cons of TypeScript vs JavaScript, we can summarize the differences between the two across various parameters:

1. Data Binding: TypeScript uses features like types and interfaces to describe the data being used while JavaScript offers no such neatly-defined classification.
2. Typing: TypeScript is a strongly typed language whereas JavaScript is a loosely typed one. TypeScript, unlike JavaScript, allows you to enforce type rules. 
3. Learning Curve: TypeScript has a steeper learning curve as compared to JavaScript as it requires knowledge of JavaScript.
4. Prototyping: TypeScript allows prototyping to clone objects without knowing their exact classes. This feature is not available in JavaScript.
5. Error Detection: Early error detection is made possible in TypeScript due to its pre-compilation debugging. JavaScript detects errors during runtime.
6. Community: TypeScript’s community doesn’t hold up against JavaScript’s huge community of developers.
7. Compilation: TypeScript, being a transpiler, needs to compile to JavaScript code before it can run. JavaScript needs no compilation.
8. Annotation: Developers need to annotate their code in TypeScript to make the most of its features. No such annotation is needed in JavaScript.

 

JavaScript vs. TypeScript: Which Is Better?

The decision to choose one or the other language depends on your use case and the unique cost-benefit analysis of your business. Neither language is inherently better on all counts. They’re better suited to different development scenarios.

If your project is limited to a few hundred lines of code, TypeScript will be overkill. JavaScript would be the ideal choice for such a project. But if you’re eyeing a complex project with multiple developers, you can fully reap the added benefits of TypeScript.

If you require a specific framework not supported by TypeScript or if your developers are already using test-driven development, the costs of moving to TypeScript will not outweigh the benefits gained.

Will TypeScript Replace JavaScript?

In one word—no. 

TypeScript is a different programming language, suited to different use cases. The question of replacing JavaScript doesn’t arise. JavaScript is one of the most popular and essential building blocks of the web and is not going away anytime soon.

While TypeScript enjoys several advantages over JavaScript, it also lacks in a few areas like compilation time and framework support. TypeScript should be seen as an augmentation to JavaScript rather than a threat.

Whether you choose TypeScript or JavaScript, you’ll find yourself in the market for JavaScript developers. Trio can simplify your hiring process and give you streamlined access to world-class developers without the need for a bloated recruitment process.

As a Trio partner, you don’t incur expensive hiring costs and still get highly-trained and driven developers for your project.

Plus, you don’t even need to handle HR functions like payroll, benefits, and compliance. Trio takes care of the entire process, end-to-end.

Conclusion

JavaScript is extremely popular and fairly easy to learn. Many JavaScript developers are upskilling by picking up TypeScript as well. This makes hiring the right developers for your project trickier as you need to vet dozens, if not hundreds of candidates.

Contact Trio today to learn how we can help you tap the global talent pool of leading developers for your next project.

Functional programming has gained popularity over the past few years. With the adoption of its concepts in languages like Java and Python, developers have seen a resurgence in functional programming. Some modern languages like Haskel and Clojure are almost purely functional.

JavaScript has always been a multi-paradigm language. JavaScript’s ability to support multiple programming paradigms makes it a versatile programming language. 

In this article, we’ll discuss functional programming and its benefits in detail. We’ll look into the concepts that define functional programming as a paradigm and how to use it in JavaScript. We’ll also dive into the debate, ‘Is JavaScript functional programming?’ 

What is Functional Programming?

Functional programming is one of many programming paradigms used by developers to create a variety of applications. Functional programming differs from other approaches in that it involves primarily using functions to create and structure your code.

Functions are simply pieces of code that take arguments as inputs and spit out outputs, as desired. Designed with accomplishing a single task in mind, functions provide better modularity and reusability to your code.

Functional programming is defined by numerous features which we’ll discuss in the coming sections. One of its most defining features is that it doesn’t allow mutation or shared states for objects, unlike other programming paradigms.

Using functional programming means limiting the scope of individual blocks of code only to their designed objectives. It doesn’t allow the modification of objects to achieve a solution but uses closed functions to achieve the said solution.

What Are the Benefits of Functional Programming?

Functional programming, by design, solves numerous issues that plague older programming paradigms. This was, in part, responsible for its growing popularity over object-oriented and procedural programming.

Let’s look at some of these benefits in detail:

Integrity

Functional programming principles warns developers to avoid mutations, eliminating a huge source of potential errors and bugs in your code. 

If you detect bugs in functional programming, they’ll be much easier to spot and rectify as they’ll be limited to the scope of the respective function. You won’tneed to scan your entire codebase to find the error.

Functional programming also uses pure functions, meaning functions do not borrow any data outside their scope. This reduces the possibility for errors by a huge degree.

Comprehensibility

Pure functions don’t mutate and are consequently, much easier to understand than other constructs used in OOP or procedural programming. 

Structuring your code in functional programming is simple and straightforward as you only need to think about the scope of the individual function. You can construct a much more modular and reusable code, unlike in OOP where you need to be mindful of encapsulation, class hierarchies, inheritance, polymorphism, and various other concepts.

As a developer, you might need to radically change your thinking if you’re coming from OOP or procedural programming to functional programming.

Durability

Variables in functional programming can’t be modified once their value has been declared. This contributes to its immutability but also ensures that your program is preserved for the entirety of its run. 

Static variables ensure that your code is secure and built to last, at least much more secure than other programming paradigms. Although functional programming languages might not be the highest performing ones, these critical benefits just might make up for it.

5 Features of Functional Programming

As we mentioned earlier, there are various features that make functional programming what it is. These features ensure that you’re not simply using functions in your code and calling it a day. You’re actually abiding by the functional programming principles.

The five major features of functional programming are:

1. First-Class Citizens

Functional programming treats functions as first-class citizens. What that means is you can work with functions in much the same way as you would with variables—assigning them as a value, using them as arguments to and outputs from other functions, inserting them inside other functions, and so on.

Functions are also called first-class objects in functional programming languages like JavaScript. 

const sum = (x, y) => x + y;

const resultSum = sum(1, 2);

const sumAgain = (x, y, sum) => sum(x, y);

This kind of treatment of functions is what makes the functional programming paradigm work in languages like JavaScript.

2. Pure Functions

Pure functions are those functions that will always return the same output for a specific input. This referential transparency is one of the most common features of functional programming. Pure functions will ensure that your code is deterministic and easy to test and debug.

As pure functions always return the same output for the same input, they help minimize any unintended side effects while writing code such as modifying variables, reassigning variables, etc.

In the following example, the ‘sum’ function will always return the same output for the same input:

function multiply(a, b) {

  return a * b;

}

Impure functions, on the other hand, rely on data other than the scope of the function, and hence, lead to mutating data and objects. Look at the example below:

let count = 0;

const increaseCount = (value) => count += value;

The count variable was declared using let, hence, it can be reassigned, making the function above impure. 

Pure functions make functional programming easy to understand, test, and reuse in other areas of your code and in the future.

3. Higher-Order Functions

A higher-order function is a function that can receive another function as an argument or can return a function as its output. Higher-order functions are great for writing better and cleaner code and compartmentalizing different functionalities of your code.

The functions that serve as inputs for higher-order functions are also called callback functions. 

Working with JavaScript, you would already be working with some higher-order functions like map, filter, reduce, and more.

You can see higher-order functions in action in the example below:

const cars= ["Chevrolet", "Honda", "Hyundai", "Tesla"];

const sayHiToCars = cars.map(car => `Hello ${car}`);

Higher-order functions help developers separate the data from the logic. You can easily abstract multiple actions from each other and write more complex functions easily. 

4. Function Composition

Composition refers to structuring your functions in a way that they work together to achieve better and more efficient solutions. It can be understood as the process of combining functions in a specific order to produce new functions. 

Composing functions also allows you to simplify your functions by using them as arguments for other functions or getting them as outputs from other functions.

An example of function composition would be:

var compose = (f, g) => (x) => f(g(x));

Function composition is a crucial skill in functional programming and can take some time for beginners to master. But once you start to use it, you’ll find you’re able to write better-constructed code that’s cleaner, more readable, and easier to understand. 

5. Immutability

Immutability, as we mentioned, is one of the core features of functional programming. Immutability refers to the property of an object to not be modifiable after it is created. Immutability, as a concept, allows you to prevent unexpected consequences like mutating objects. 

Most functional programming languages enforce immutability, so you can rest assured that you won’t be unintentionally mutating objects and data. But some languages, like JavaScript, don’t give you such a guarantee, as it’s a multi-paradigm language. 

To be able to ensure immutability in JavaScript, you’ll need to ensure you’re proactively abiding by the principles we’ve discussed above. You’ll also need to get rid of a few methods you’d be used to, such as reverse, fill, splice, unshift, push, and more. We’ll discuss this more in the next section.

So if you have an object and you want to add a new element to it without modifying it, you’ll need to create a new object that’s a copy of the original object, so as to preserve immutability in your code.

const PC = {

  cpu: 'AMD',

  gpu: ‘NVIDIA’

  };

const newPC = PC;

  PC.cpu = 'Intel';

How to Apply Functional Programming in JavaScript?

One might wonder, after going through the above concepts— what is functional programming in JavaScript? How exactly should you go about using functional programming concepts in JavaScript? Especially, since we’ve already mentioned that JavaScript is not strictly a functional programming language but a multi-paradigm one.

Before we get into using functional programming in JavaScript, let’s dive a bit deeper into one of the most common queries developers have about JavaScript:

Is JavaScript a Functional or Object-Oriented Programming Language?

As we discussed above, JavaScript is a multi-paradigm language. It can’t be cleanly categorized as either an object-oriented or a functional programming language. That’s because one can easily use whichever paradigms one wants in JavaScript.

JavaScript can be shown to have elements of both OOP and functional programming. You can use objects and prototypes in it and do all manner of OOP-based computation. And, you can also use first-class functions and immutable objects in it.

JavaScript, like many other languages, lends itself to multiple programming paradigms. It’s up to the developer to decide which paradigm is better suited to the problem at hand. 

What Is Functional Programming in JavaScript?

JavaScript has some in-built functions that give it its functional programming flavor. Some of them are array.prototype.join, array.prototype.filter, and string.prototype.slice.

JavaScript also has const declaration, which also lends itself beautifully to functional programming, since it ensures there’s no data mutation happening.

Now, let’s look at some other functions which can help you apply functional programming in JavaScript:

Map

The map function maps each item of an array to a function and creates a new array based on the outputs from the function.

To use map, we first declare a function in JavaScript and then use map to arrive at the new array.

const triple = x => 3 * x;  

[1, 2, 3].map(triple);  

// [3, 6, 9]

In this example, triple acts as a mapper function and accepts each item of the original array, computes the return value, and the values are then used by map to create the output array.

Filter

The filter function is used to filter the values of an array, based on a condition that is declared as a function. 

The following example is used to filter even values from an array:

const filterEven = x => x%2 === 0;  

[1, 2, 3].filter(filterEven);  

// [2]

Concat

Concat, as you can guess, can add new items to an array, creating a new array. Notice that concat is different from the push function, as push mutates the data, but concat, being a pure function, doesn’t. 

[1, 2].concat([3, 4])  

// [1, 2, 3, 4]

Reduce

The reduce function is used to truncate an array to a single value, based on a reducer function. This reducer function takes each item of the array, one by one, along with the accumulated value and returns the new value.

It keeps doing this till it arrives at a single value.

const sum = (accumulatedSum, arrayItem) => accumulatedSum + arrayItem  

[1, 2, 3].reduce(sum);

// 6

Conclusion

Functional programming has quickly gained favor from developers and organizations, and not without reason. The benefits of functional programming, especially in JavaScript, are manifold. You can easily write cleaner and more comprehensible code that’s free from side effects and easy to debug.

This is not to say that functional programming is the be-all and end-all of all programming. But it certainly lends itself perfectly to many programming problems. No wonder global technology organizations like Google, Meta, Netflix, Uber, and more use JavaScript to design best-in-class experiences for their customers.

If you’re also looking to hire JavaScript for your new project, then Trio is a great place to start. Trio developers are thoroughly-vetted professionals who’re some of the best in their niche. They also receive excellent professional and personal support from Trio, leading to increased job satisfaction and low turnover.

What’s more, you can hire near-shore Trio developers at a fraction of the cost of conventional hiring and you don’t even need to handle HR responsibilities like payroll, benefits, and compliance.

Contact us today to learn more about hiring JavaScript developers at Trio and give wings to your exciting new project.

 

Hiring developers is often a more painstaking task than the hiring process in other fields. 

This is because software development is a very technical field. And you need to make sure your job candidates are up-to-date on the tools and skills necessary to build your software project. 

When it comes to JavaScript developers, you will want to have a handcrafted set of JavaScript interview questions to truly test your potential hire’s knowledge. 

These 11 JavaScript developer interview questions are a great place to start. Check them out below!

1. Name two principle programming paradigms for JavaScript development. 

JavaScript is a multi-paradigm programming language that supports:

• Imperative/procedural programming
• Object-oriented programming (OOP)
• Functional programming 
• Prototyped-based programming or prototypical inheritance (an extension of OOP)

Your candidate should be able to name at least two of the above programming paradigms. Although it might be a red flag if there’s no mention of object-oriented programming whatsoever. 

2. Describe the difference between one-way data flow and two-way data binding. 

In unidirectional or one-way data flow, data can only go to one destination. 

For example, a change in the presentation layer or view in a JavaScript program does not change the model or business logic behind the scenes. 

The advantage of this approach is that code is typically easier to debug and there are fewer errors overall. 

On the other hand, in bidirectional or two-way data binding, the data flow can take place in both directions. 

This is what distinguishes Angular vs. React, two prominent JavaScript frameworks. 

Angular’s bidirectional binding means that changes in the model or view of the software architecture ultimately affect one another. 

Two-way data binding can be an effective strategy if you want to share data between a component class and its template. 

3. What are the pros and cons of monolithic versus microservice architecture?

Pros of monolithic architecture: 

• Simplifies cross-cutting concerns where aspects are inevitably intertwined 
• Performance advantages; monolithic programs are simpler and easier to process in memory

Cons of monolithic architecture:

• Tight coupling; the interdependency of components complicates scalability and code management 
• The same tech stack must be used throughout the application 

Pros of microservice architecture:

• Loose coupling; the lack of dependencies means that code is continuously adaptable
• Scalability; functions are composed as services so scaling can happen on a component basis rather than holistically 

Cons of microservice architecture:

• It’s hard to find talented developers who can implement microservices within your software product
• Testing is more difficult 

4. What is a closure in JavaScript? Provide an example. 

A closure is a function that has access to variables and/references outside of its standard scope. 

function hireDevs() {
  var name = 'Trio';
  function displayName() {
    alert(name);
  }
  return displayName;
}

var myFunc = hireDevs();
myFunc();

In most programming languages, the code here would not run. Traditionally, local variables within a function only exist for the duration of the function’s execution. 

However, print this code in any JavaScript editor and you’ll get a pop-up alert reading “Trio” just the same. 

JavaScript functions form closures using a lexical environment consisting of any local, in-scope variables at the time of the closure’s creation. 

Since a normal function does not have this capacity, it’s imperative that your JavaScript developer knows how to describe and apply this principle in action. 

5. Name and identify the basic data types of JavaScript.

JavaScript has seven basic data types, which should be easy enough for any JavaScript developer worth their salt to remember. 

Most JavaScript developers prepare for the interview process ahead of time, so it’s important that your candidate is well-studied. 

Boolean — returns true or false

Null — represents unknown values, empty, or nothing

Number — used for integers and floating-point (decimal) values

Object — can store data or other complex entities 

String — for any combination of alphanumeric values

Symbol — creates unique identifies for objects

Undefined — value not assigned 

6. Explain the call() method. 

The call() method points to JavaScript’s object-oriented capabilities. It invokes a method by specifying the owner object. 

Essentially, this allows developers to use the method of another object and also use its corresponding arguments. 

This ability relies on the implied JavaScript rule that if a function is not a method of a JavaScript object, it is a function of the global object. 

7. What’s is the use of the NaN() function?

The NaN() function has only one purpose — to check whether a value is an illegal number. 

The program will return a Boolean object of true or false. Applied aptly, the function can mitigate many runtime errors. 

8. What will “console.log(1 < 2 < 3); console.log(3 > 2 > 1);” return?

You probably recognize these logical operators from an elementary math class years ago. However, they don’t quite work the same in JavaScript. 

The first statement returns true but the second returns false. This is because JavaScript reads from left to right, and evaluates expressions one-on-one. 

For the first statement, it is true that one is less than two and two is less than one. Makes sense, right?

In the second statement, three is more than two, so you’re still on the right track. But at this point, JavaScript returns the entire expression as true. 

Now, the comparison is between true and one. Ironically, JavaScript does have a numerical value for true, which is equal to one. 

However, one is definitely not more than one, making the entire statement false. 

9. What does the ‘this’ keyword do?

The this keyword is a self-reference for JavaScript objects. Simply put, it’s a way to refer to the current object within the class definition itself.  

10. Describe the various ways to create an array object in JavaScript.

There are three different ways to create an array in JavaScript. 

• Create an instance of an array 
  Ex: var exArray = new Array();
• Use an array constructor
  Ex: var exArray = newArray(“hire”,”Trio”,”developers”);
• Use an array literal
  Ex: var exArray = [“hire”,”Trio”,”developers”];

11. What is JavaScript?

As a bonus, your JavaScript developer interview questions should include at least one question asking the interviewee to describe JavaScript in layman’s terms. 

Keep this question open-ended, so you can see how much or how little your potential hire knows. 

First and foremost, they should make a point to explain what JavaScript is used for. 

JavaScript is a front-end programming language. Along with CSS and HTML, it is the backbone of nearly every website’s user interface (UI). 

Thanks to the interactivity JavaScript provides, there are many JavaScript examples demonstrating the language’s capability in web applications, mobile applications, and even games. 

You should expect a JavaScript developer to know this information. You don’t want to work with a developer who doesn’t know the tools they’re working with. 

Conclusion

These JavaScript developer interview questions only break the surface of what an experienced JavaScript developer should know. format 

Don’t be afraid to add a dozen or more questions to really challenge the job applicant. Of course, this is only the technical interview. Next is the coding challenge!

But if you’re feeling overwhelmed by all the resumes, technical interviews, coding challenges, and general frustrations of the hiring process, you’re not alone. 

For many business owners, this is the most difficult part of software development. 
This is why Trio exists. We endeavor to help businesses in need meet their objectives without all the paperwork. 

Find qualified JavaScript Developers at Trio today!