The Revealing Module Pattern Learning JavaScript Design Patterns Book

By selectively exposing the private methods and variables of a module, it allows developers to control how and when the module is used and promotes a more structured and organized codebase. Both the module and revealing module patterns should be used to protect variables and functions that you do not wish to share with the outside world. I would favor revealing module pattern for it’s a much cleaner way of defining public APIs and improving code readability. The revealing module pattern is much easier to use and modify. The purpose of the revealing module pattern is to maintain encapsulation and reveal certain variables and methods returned in an object literal.

To make this guide a bit more tangible, we’re going to build a few different libraries around a set of helper functions that perform basic math. Get Mark Richards’s Software Architecture Patterns ebook to better understand how to design components—and how they should interact. Since our function has no name, we call it an expression.

• What if we could combine this pattern with the Prototype Pattern though to get the benefits provided by prototyping?
• If you look at the return statement, the values of variables and functions can be returned in a conventional JavaScript way.
• I also like the fact that it doesn’t separate code into constructor and prototype sections.
• While the code works fine this way, I’ll examine how we can restructure it to follow the Revealing Module Pattern.

In addition, you probably would never notice performance problems until you start hitting thousands or hundreds of thousands of instances of a module on a page. When is the last time you ran into a situation like that? As you can see, the publicFunction is accessible from the outside of the module, but the privateFunction is not. By keeping the private methods and variables hidden, we can ensure that they are not accidentally modified or accessed by other parts of the application, which can lead to unexpected behavior. If you look at the return statement, the values of variables and functions can be returned in a conventional JavaScript way. We are using the addProperty, removeProperty, and displayPerson as pointers to the private functions.

Javascript

The Run Python Script with parameters on Button click is used to provide an abstraction over private implementations by providing public APIs. Since the function ‘callAddPropertyFn’ is inside the IIFE, it has access to all private variables and functions. We return a public method ‘callAddPropertyFn’ from the IIFE. You can verify it by adding a console.log outside the IIFE. Developers are always interacting with and creating design patterns, even when they don’t realize it.

I think worth explaining that the using the IIFE assignment is a singleton pattern, which takes away the ability to create multiple instances of the module. You can add some changes to above code to make it more readable, if you have too many methods inside your module. Private methods and functions lose extendability since they are unaccessible . If you console.log, then you’ll get ‘undefined’ since nothing is returned by this function. The IIFE contains a private ‘person’ object and a private function ‘addProperty’ that accepts a property name and a property value.

We can only use the public method, which is the publicGetName function, to return the name. This gives us the ability to create encapsulation within our code. We defined a function, using IIFE inside it, that returns an object.

As we wrap up this tutorial, we have found that the Remote Web Developer Salary gives us a nice way to encapsulate variables and functions into a reusable object. It’s quite similar to the module pattern itself, however you might like the revealing module pattern better for it’s easier to read format. Like other software patterns, it helps us to ease maintenance, foster code reuse, and minimize naming collisions in the global namespace. We get the benefits of the module container, an easier to read api, and the ability to new up as many instances as we like.

The Revealing Module Pattern

Note that in the object literal, the name of they key of each key/value pair, is the name of the exposed member. In our example here we simply returned a one to one mapping of alias to name for the public members. If you wanted to name your function one thing on the inside of the module, and expose it publicly as another name to external callers, you can do that as well. In our example we have a gofast() function and that is how we call it on our instances. What if you wanted to have people call that function using blastoff instead of gofast? The Revealing Module Pattern is a powerful and flexible design pattern that can be used in JavaScript development to create reusable and maintainable code.

This is because the private function will continue to refer to the private implementation, and the pattern doesn’t apply to public members, only to functions. Then we return an object with the functions that we’d like accessible in other files. From this function, you return an object containing methods you want to expose to public code to call. The revealing module pattern is exactly like the module pattern but with a small twist. Let us take the above example and add another method ‘removeProperty’ to the IIFE.

Revealing Module Pattern – Techniques, Strategies and Patterns for Structuring JavaScript Code

The app development team has created an integration Scoped App that allows ServiceNow to integrate multiple file storage repositories into a single repository. The underlying implementation is somewhat complex involving a local file cache, web services, and rules to determine which file store is used for different processes. The short answer is that the RMP is an anti-pattern so you shouldn’t use it. The code sample you showed is more of a mixin pattern to me, so it’s more flexible than the original module pattern, but both require the same understanding to execute correctly. If you pose an actual stackoverflow question, I can give a more detailed answer. In the following example, you can see how, in contrast to RMP, the function definitions are actually in the return object literal, and references to members are qualified by this.

You can invoke the function ‘callAddPrpertyFn’ from outside the IIFE function as shown below. We will first create an IIFE and assign it to the constant module. If you want to make name and sayHello private as before, the references to the now-private members have to be changed. References to public members are via this, whenever possible. By resolving the ambiguity differently, you get variants of the Module Pattern.

Using the JavaScript Revealing Module Pattern

May be it is safer if call private function by passing this to it, so private function could reference public function with this variable. In Revealing Module pattern, we define functions in closure area and only use variable names in returning object. With that one small change, you can now call code such as model3.blastoff() and roadster.blastoff(), and behind the scenes, it is actually the gofast() function providing the implementation for you. It is a simple method of creating aliases for the functions you want to make public. Name them however you like, as long as they make sense to you. You can still make use of the new keyword with the revealing module pattern if you like.

Revealing Module Pattern

The core aspect of the Revealing Module Pattern is the use of a closure which returns the public interface for the API. In our example, the public interface includes both the getFile and saveFile functions. But under the hood, you can see many internal functions which are not accessible to the outside world. The Class Pattern and Namespace Pattern have no similar capability, all functions and properties are considered public. I created a revealing module pattern with following code. Because we’re not returning our private method, it is not available outside the module.

This little outline we have above is an example structure of the revealing module pattern. At first glance, it does indeed look quite similar to the module pattern that we already had a look at. This is not an actual requirement, but it is a good idea from a conventions standpoint, as it gives an indication that the new keyword is not required with the revealing module pattern.

Now, you can access any of the utility functions by calling them on the calculator namespace. This pattern lets you scope all of your functions to a specific namespace, How To Become a Front-End Developer which helps prevent naming collisions with other functions. We’ll create a few libraries from these functions, using different programming patterns and techniques.

A well-designed module should export only a simple interface and keep the irrelevant logic private and inaccessible. Public object members which refer to private variables are also subject to the no-patch rule notes above. All members, whether public or private, are defined in the closure. Now, imagine that we define a new variable inside our function and we want it to be private—that means there’s no way we can access it outside the scope of the function. The module pattern is quite similar to an IIFE , but a module always returns an object instead of a function. Public object members that refer to private variables are also subject to the no-patch rule.