6 Differences Between Arrow Functions and Regular Functions in JavaScript
Functions are an essential part of JavaScript that you need to use to write reusable code. The two main types of function are regular and arrow functions, and there are many ways to define them.
Even though they fill similar needs, they have a few critical differences that can fundamentally influence how you use them in your code. Learn all about several differences between arrow functions and regular functions.
1. Syntax Differences
The syntax you choose when developing JavaScript functions has a big impact on how simple it is to read and comprehend your code. The syntax of regular and arrow functions differ significantly, impacting how you write and use them.
JavaScript arrow functionsuse a smaller language structure that is more understandable. you may use them to create functions by combining them into a single expression or statement.
In this example, theaddfunction accepts two inputs,aandb,and returns their total. The=>sign defines this as an arrow function.
On the other hand, defining a regular function requires the use of thefunctionkeyword, with a more verbose syntax, as shown in this example:
In this example, thefunctionkeyword defines a regular function which also uses curly braces and thereturnstatement.
Regular functions are more useful for complex syntax requiring multiple statements or expressions. In contrast, arrow functions use a more concise syntax that can make your code easier to read and understand.
2. Scoping Differences
The term “scoping” describes how a function’s internal variables and functions are accessible. In JavaScript, you define and access variables and functions throughout your code using scoping. Their distinctscoping can significantly impact how you write and use JavaScript’sarrow and regular functions.
In scoping, how arrow functions handle thethiskeyword differs significantly from how normal functions do. Regular functions define thethiskeyword themselves; therefore, it can change depending on the context in which you invoke the function.
On the other hand, because they do not specify thethiskeyword, arrow functions use the samethisas the static scope surrounding them.
To see the difference, check out the following example. Let’s say you have apersonobject with anameproperty and a method calledsayName()that logs the person’s name using a regular function:
Here, the regular sayName() function is a method of the person object and thethiskeyword inside that function refers to that person object.
Let’s now try the same thing with an arrow function:
Because the arrow function used in thesayName()method does not define its ownthiskeyword, it uses thethisof the static scope that surrounds it. In this case, that’s the global scope of the instance.
As a result, when you callperson.sayName(), you getundefinedrather than"John.“This can significantly impact how you write and use functions in your code.
3. Use Cases and Best Practices
Regular functions are better suited for functions that require their ownthiskeyword, such as methods in an object.
Arrow functions are better suited forfunctional programmingand callbacks that do not requirethiskeyword.
4. Function Binding Differences
Function binding is the term used to describe the relationship betweenthiskeyword and functions in your code. The variations in function binding between arrow functions and normal functions can strongly impact how you construct and use arrow functions.
Using thethiskeyword makes it unique in regular functions and associates with various objects based on the method used to call the function. Function binding is one of the most important distinctions between regular and arrow functions.
In contrast, arrow functions do not havethiskeyword; rather, they get it from the surrounding scopes.
Let’s look at an example to understand more on this difference. Assume you have apersonobject with anamefield and a method calledsayName()that uses a regular function to record the person’s name:
In this example, you call the person object’ssayName()method with the valueanotherPersonusing thecall()method. Because of this, thesayName()method,this, keyword is bound to theanotherPersonobject, and it logs “Jane” rather than “John.”
Let’s now use the same thing with an arrow function:
Since thesayName()technique doesn’t have its own keyword, you’re using an arrow function within it in this example. In this case, the arrow function inherits the properties of the surrounding scope, which is the global scope.
This means that when you runperson.sayName.call(anotherPerson), the arrow function’sthiskeyword remains the global object, andundefinedtakes the place ofJanein the log.
If you need to bind a function to a specificthisvalue, an ordinary function may be preferable. However, if you don’t need to bind a function to a specificthisvalue, an arrow function might be shorter and easier to understand.
5. Implicit Return
Arrow function have an implicit return feature. If the function body consists of one single expression, the functions returns that expression.
As an example:
This arrow function returns a double from a parameter. You do not need to use an explicitreturnkeyword because the function body only has one expression.
6. Compatibility Differences
Compatibility differences refer to the ECMAScript 6 added arrow functions, which may not work with older browsers or environments. On the other hand, regular functions have been around since the beginning of JavaScript and are widely supported.
Here is an illustration of an arrow function that may not work in more established conditions:
The following is a comparable regular function that ought to work in most situations:
Use regular functions rather than arrow functions when targeting older environments to ensure compatibility. However, arrow functions can provide a syntax that is easier to understand and more condensed when working with modern browsers and environments.
Choosing Between Arrow Functions and Regular Functions in JavaScript
In JavaScript, arrow and regular functions have distinct features and applications. Arrow functions have a simple syntax, inheritingthiskeyword term from the context of their use while regular functions are more adaptable and can deal with more complex situations.
It is critical to know how they differ and how to use them as per your code’s requirements. When selecting which kind of function to use, you should also consider compatibility differences.
Ultimately, JavaScript’s arrow and regular functions are powerful tools that help you write cleaner and more efficient code.
There exist additional differences between the two apart from the syntax.
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