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. Note that in the object literal, the name of they key of each key/value pair, is the name of the exposed member.

Sometimes called encapsulation, it protects the value inside a module from being accessed from other scopes. One advantage of the revealing module pattern is that you can include functions and variables that are private, and cannot be accessed or used outside of the library. Our function-level scope still keeps our methods and variables public and private based on whether we expose them in the return object. With a plain object, the getTotal() function would be a public method as part of the library. With a revealing module pattern, we can keep it private and for internal use only. This pattern allows the syntax of our scripts to be more consistent.

revealing module pattern

Of course the example names here are far from what I would use in a real script, but it shows the power of this pattern. During a Q&A session in a training in Hongkong yesterday I showed this to Douglas Crockford and asked him what he thinks of it. He didn’t mind the idea, but considered even the pub object redundant. Demos of all the patterns covered in this series can be downloaded below.

Explanation of useCallback() hook in React.js

To me it’s greatest power is as an instantiable module; each instance having its own ‘configuration’ and ‘state’. It’s like a React hook or similar component that provides shared-logic. You can use double underscore prefix for event binding function, to separate it from private functions. Note that unlike RMP, in order to make name and sayHello private, the references pointing to name and sayHello in the various function body definitions also have to be changed. The function ‘addProperty’ will not be invoked while running the IIFE and hence the console.log statement inside the function will not run.

revealing module pattern

Making your application reusable is the best to ensure that it will have rich, well-written code. We should always ensure to write the best code possible and the module pattern can help us with that. Let’s have a look at the Six Strategies for Reducing Labor Costs VonLehman below illustrated pictorial representation which will help us to understand this design pattern more nicely as well as clearly. Now, you can access any of the utility functions by calling them on the calculator namespace.

Interface Design Patterns: Revealing Module Pattern

Can be repurposed to return any of the previously mentioned Patterns yielding the advantages of other patterns while mitigating the disadvantages. For this solution, we will create a Script Include which can be accessed by all Scopes but is ultimately Protected to mask the source code when purchased from the store. If you wanted to make name and sayHello private, you just need to comment out the appropriate lines in the return object. Telerik and Kendo UI are part of Progress product portfolio.

  • In other words, what is contained in the return statement of the revealing module pattern is different than what is in the module pattern.
  • The Revealing Module Pattern builds on the traditional module pattern by selectively exposing the private methods and variables of a module.
  • With the revealing module pattern, there is no need to do this!
  • Note that unlike RMP, in order to make name and sayHello private, the references pointing to name and sayHello in the various function body definitions also have to be changed.

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.

Create Node js-express API from Scratch

However, you can achieve the same effect through the clever application of Javascript’s function-level scoping. The Revealing Module pattern is a design pattern for Javascript applications that elegantly solves this problem. Before ECMAScript 2015, JavaScript language was lacking an official module system. Lack of namespacing and protecting against polluting the global environment forced developers to design many solutions for this problem. 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.

revealing module pattern

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. May be it is safer if call private function by passing this to it, so private function could reference public function with this variable.

The purpose of the revealing module pattern is to maintain encapsulation and reveal certain variables and methods returned in an object literal. This keeps the syntax of the whole script consistent and makes it obvious at the end which of the functions and variables can be accessed publicly. The other benefit is that you can reveal private functions with other, more specific names if you wanted to. The revealing module pattern is not perfect, in fact it shares the same drawbacks as is found with the module pattern.

JS Design Patterns: Module & Revealing Module Pattern

We need to access some methods, but shouldn’t be able to mess with other methods or variables. Following this technique, multiple objects can be created as needed in a page or script. Keep in mind that each call to Calculator() places a new copy of each function in memory, but the impact is quite minimal in this case. If you’re worried about multiple copies of functions being placed in memory as objects are created then consider using the Revealing Prototype Pattern since it leverages JavaScript prototyping.

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. The module pattern is yet another way of declaring and making reusable code. Javascript does not have the typical ‘private’ and ‘public’ specifiers of more traditional object oriented languages like C# or Java.

Revealing module pattern is a design pattern, which let you organise your javascript code in modules, and gives better code structure. It gives you power to create public/private variables/methods , and avoids polluting global scope . As we wrap up this tutorial, we have found that the revealing module pattern gives us a nice way to encapsulate variables and functions into a reusable object.

We don’t have access modifiers (keywords in object-oriented languages that set the accessibility of classes, methods and other members) in JavaScript, and this is why the scope is very important. For every programming language, there are design patterns that were created throughout the years, based on the experience of many developers. Design patterns are proven solutions, tested many times, that improve communication and make code reusable. To create a revealing module pattern, you assign an immediately invoked function expression to a variable. He also disliked the Module pattern’s requirement of having to switch to object literal notation for the things he wished to make public. The beef I had with that is that you need to repeat the name of the main object when you want to call one public method from another or access public variables.

I send out a short email each weekday on how to build a simpler, more resilient web. It’s only intended to be used inside other functions in our library. We can abstract that bit of code into a getTotal() helper function. 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.