How to Import and Export Functions in JavaScript
Today, JavaScript plays a huge role in website development. Front-end developers use JavaScript to create interactive web applications. As a result, there’s been an increase in demand for JavaScript developers.
Certainly, JavaScript has evolved over the years. ES6 introduced many new features to the language. One of these is a way to easily share codes among JavaScript files.
Function import and export for JavaScript are new features that will make you a better developer. Here’s how these features work.
What Is a JavaScript Module?
A JavaScript module is a JavaScript file that contains a collection of code for you to use. Modules are usually written in separate files and imported using theimportkeyword. It saves time and effort because it’s possible to reuse it later.
For example, if you have a function calledcalculateSum(), you’re able to include it in another file and make it available anywhere in your project using theexportandimportJavaScript functions without any fuss.
One of the benefits of using modules is that it helps to keep your code organized. It also makes your code more manageable and easier to debug.
In order to use a JavaScript file as a module, you need to create a script in your HTML document with atype=“module”.
There are two types of modules:
We’ll focus on the ECMAScript Modules here. If needed, see ourintroduction to JavaScriptto brush up on the basics.
How to Export Functions in JavaScript
In JavaScript, functions are first-class objects that can be passed as arguments in addition to being used on their own. Exporting functions is a good way to transfer them into other programs. It’s also used when you want to create reusable libraries.
Exporting functions in JavaScript is done using theexportfunction. Theexportfunction exports a given function to be used by another file or script. By exportingour own functions, we can freely use them in other files or scripts without worrying about licensing issues.
There are two ways to use theexportfunction efficiently. We’ll go over these with code examples.
Suppose you have a filegetPersonalDetails.jswhich has a function that returns the full name of a user after a prompt input. The function looks like this:
You can export multiple functions by using the first method. This is done by including the names of the desired functions in the curly bracket. The functions are separated by comma.
For example: Suppose you have three functions in ourgetPersonalDetails.jsfile- getFullName(),getEmail(),getDob(). You can export the functions by adding the following line of code:
export {getFullName, getEmail, getDob};
How to Import Functions in JavaScript
In order to use a module, you first need to import it. Any function can be imported using a full-path reference.
Importing functions is quite straightforward. JavaScript has a built-in feature to import your own functions from other files. If you want to access those functions from other modules, it’s a good idea to include a function declaration for each of your utilities.
A function to be imported is already exported in its original file.
You can import functions from a different file using theimportkeyword functionality.Importallows you to choose which part of a file or module to load.
Here’s how you import ourgetFullNamefunction fromgetPersonalDetails.js:
This will make this function available for use in our current file.
to import multiple functions, the functions to be imported are included in the curly braces. Each is separated by a comma (,).
There is another way to use theimportfunctionality. This allows us to import all the exports in a particular file. It is done using theimport * assyntax.
you’re able to import all the exports in ourgetPersonalDetails.jsby adding the following line of code:
The above will create an object calledpersonalDetailsModule.
This is just a variable name, you can name it anything.
This object contains all the exports in ourgetPersonalDetails.js.The functions are stored in this object and can be accessed the way you access any object property.
For example, We can access thegetFullNamefunction by adding the following line of code
What Is Export Default?
Export defaultis an exceptional export functionality. This is used if only one variable is being exported from a file. It is also used to create a fallback value for a file or module.
Below is an example where we used thegetFullNamefunction as a default:
You cannot have more than one value as a default in each module or file.
A Function used as default is imported differently. Here’s how to import ourgetFullNamefunction used as default:
Here are the differences:
Supercharge Your JavaScript Functions
JavaScript modules are pieces of code that can be reused in other parts of your code, using the import and export JavaScript functions. They’re usually written in separate files, and imported using the import keyword. One of the benefits of using modules is that it helps to keep your code organized. It also makes your code more manageable and easier to debug.
Want to be better at web development? Arrow functions, added to JavaScript ES6, give you two ways to create functions for web apps.
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