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Fat Arrow Function Javascript: Javascript Explained

Table of Contents

Fat arrow function JavaScript is a new type of function that was introduced in the ECMAScript 2015 specification. This function has become increasingly popular for its convenience and readability, as well as its potential to help developers simplify their code. In this article, we’ll discuss what a fat arrow function is, the benefits of using them, and how to write them. We’ll also look at how they differ from other types of functions, common use cases for them, pitfalls to avoid when working with them, tips and best practices for writing them, and finally, how to write a fat arrow function.

What is Fat Arrow Function Javascript?

A fat arrow function is defined using the “=>” syntax after the parameters of the function. This type of shorthand is often referred to as the arrow function syntax. The arrow indicates that the function definition is coming after the parameters.

For instance, in the following example of a function that takes a single parameter and returns its value, we can see this syntax in action:

const doSomething = (param) => { return param;};

Here all that is required is the parameter in parentheses, followed by the “=>” arrow syntax, and then the code block, which in this case is simply a return statement.

Fat arrow functions are a great way to simplify your code and make it easier to read. They are also useful for creating anonymous functions, which can be used to pass functions as arguments to other functions. This makes it easier to write code that is more concise and easier to understand.

Benefits of Using Fat Arrow Function Javascript

The main benefit of using the fat arrow function syntax is to optimize code readability. Arrow functions are generally easier and more succinct than traditional function syntax, allowing developers to write more concise, readable code. This is especially useful when writing code that involves callbacks and/or when multiple functions are nested within each other.

Also, because arrow functions don’t bind their own this, they are often referred to as Lexical this: their this is determined by the context in which it is used.

Finally, arrow functions can be used to simplify object methods. When defining an object method with the conventional syntax, the code gets a bit verbose. The following example illustrates this:

const obj = { someProp: "someValue", someFunction: function(arg1, arg2) { // do something } };

In the above example, adding an object method requires us to write out the keyword function. This can be simplified using an arrow function syntax like so:

const obj = { someProp: "someValue", someFunction: (arg1, arg2) => { // do something } };

Using arrow functions can also help to reduce the amount of code needed to achieve the same result. For example, if you wanted to create a function that returns the square of a number, you could use the traditional syntax like so:

function square(x) { return x * x; }

This can be simplified using an arrow function like so:

const square = x => x * x;

How to Write a Fat Arrow Function

Writing a fat arrow function involves following a few basic steps. First, define the parameters that will be accepted by the function using conventional parentheses enclosing them. An empty set of parentheses should be used if the function doesn’t accept any arguments.

Next, add the “=>” arrow syntax after the parentheses to indicate a fat arrow function.
Then, write out the code block enclosed in curly brackets that will be executed when the function is called.

For instance:

const doSomething = (param) => { // execute some code here };

It is important to note that fat arrow functions do not have their own this context, and instead use the this context of the enclosing scope. This can be useful for writing concise code, but can also lead to unexpected behavior if not used carefully.

How Does the Fat Arrow Function Differ From Other Types of Functions?

The primary differences between fat arrow functions and other types of functions are that fat arrow functions don’t have their own this, arguments, super, or new target. Instead, they use the this, arguments, super, and new target of the enclosing scope in which they are defined.

They also don’t have their own prototype, meaning they can’t be used with the new keyword. In addition, they can’t be used as constructors.

Common Use Cases for Fat Arrow Functions

Fat arrow functions are commonly used in situations where writing a traditional named or anonymous function would have been an awkward or inefficient approach. For instance, they can be used for dealing with callbacks or for returning an object from a given set of parameters to replace anonymous functions.

Some other common use cases for fat arrow functions include:

  • Iterating over array values: In this case, you can use the fat arrow function syntax to create a concise one-line loop instead of having to write out an entire anonymous function.
  • Passing functions as callbacks: Because of their conciseness and readability, fat arrow functions are a great choice for passing as callbacks.
  • Filtering array values: Again, they are useful in limiting code verbosity when it comes to filtering array values.

Pitfalls to Avoid When Working with Fat Arrow Functions

Unintentional global variables. This is an easy trap to fall into with fat arrow functions. Because they do not bind their own this, any variable declared inside an arrow function will automatically be global, meaning it will be available to any other code running in your program. To prevent this from happening accidentally, you should always have your variable names properly scoped.

Assigning a return value. When working with arrow functions, you must remember that you cannot use the return keyword as you would with other types of functions; instead you need to assign the return value as part of your fat arrow syntax. All of this means that it’s important to pay attention when working with arrow functions.

Tips and Best Practices for Writing Fat Arrow Functions

  1. Always enclose fat arrow functions in parentheses.
    This helps prevent errors that could arise when multiple functions are nested within each other.
  2. Pay close attention when assigning a return value.
    Remember that you cannot use the return keyword with fat arrow functions; you must assign the return value instead.
  3. Scope your variables properly.
    Because arrow functions do not bind their own this, any variables declared inside them will become global variables unless you scope them properly.
  4. Conclusion

    Fat arrow functions have been around for several years now, but their popularity has grown drastically in recent times. As developers attempt to write more concise code for greater readability and maintainability, optimize their use of callbacks, or use objects more efficiently, fat arrow functions offer a great way to make all these tasks easier.

    In this article we discussed what a fat arrow function is, its benefits and how to write one. We also looked at how they differ from other types of functions, common use cases for them, pitfalls to avoid when working with them, tips and best practices for writing them, and finally how to write a fat arrow function.

Anand Das

Anand Das

Anand is Co-founder and CTO of Bito. He leads technical strategy and engineering, and is our biggest user! Formerly, Anand was CTO of Eyeota, a data company acquired by Dun & Bradstreet. He is co-founder of PubMatic, where he led the building of an ad exchange system that handles over 1 Trillion bids per day.

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