Revealing Module Pattern in Javascript & quick tips by Rahul Sagore

You can add some changes to above code to make it more readable, if you have too many methods inside your module. This pattern is well known as a Immediately Invoked Function Expression or IIFE. Its also a good practice to run your modules in ES5 strict mode.

  • The reason no new keyword is required is because of those two little parenthesis after the function declaration.
  • Here’s an example using the _.eq() method from lodash.
  • The biggest advantage of revealing module pattern as compared to the module pattern is the code readability aspect.
  • Then we would have multiple instances of musicPlayer floating around, polluting our environment and causing all sorts of confusion.
  • With the revealing module pattern, there is no need to do this!

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. Simply leave off the immediately invoking () parenthesis after the module declaration, change the module name to lowercase , then new up at will.

Private methods and functions lose extendability since they are unaccessible . For example, all four of our calculator functions include a bit of code that checks how many numbers were passed in. Then removes the first one and uses it as the starting total. 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, which helps prevent naming collisions with other functions.

Revealing Module Pattern in Javascript & quick tips

The module pattern is easy to use and creates encapsulation of our code. Modules are commonly used as singleton style objects where only one instance exists. The Module Pattern is great for services and testing/TDD.

Let’s have a look at the below illustrated pictorial representation which will help us to understand this design pattern more nicely as well as clearly. Nice explanation, but can someone give the advantage and the disadvantage of using this design pattern. As a result of this, modules created with the may be more fragile than those created with the original Module pattern, so care should be taken during usage. Public object members that refer to private variables are also subject to the no-patch rule.

Rock, Paper, Scissors, and the Revealing Module Pattern

I’m keen to get some feedback on how I have utilized the Everything You Need to Know About Hiring Node js Developers in 2022 here. This code is part of a web application that is used by the public. Actually, given that now all our functions are private, the problem is worse. Using our learning experience platform, Percipio, your learners can engage in custom learning paths that can feature curated content from all sources. This post covers patterns and techniques found in Dan Wahlin’sStructuring JavaScript Codecourse on Making statements based on opinion; back them up with references or personal experience.

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 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.

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. In fact, the outside world doesn’t even know they exist. The Class Pattern and Namespace Pattern have no similar capability, all functions and properties are considered public. At the end of your code, you return an object with any of the functions that you want to make publicly available.

revealing module pattern

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. The reason no new keyword is required is because of those two little parenthesis after the function declaration. The biggest difference between the module pattern and the revealing module pattern however is in fact in the return statement. Recall that in the module pattern, we defined our public functions right in the returned object literal. With the revealing module pattern, there is no need to do this!

So we can create closure and be more sensible at protecting our code. It’s not all about protection however, there are also naming conflicts. I bet when you first started out writing jQuery/JavaScript, that you dumped all your code in one file and it was just function, function, function. Little did you know these were all global, and you probably suffered the consequence at some point. If so, you’ll learn why, and what to do to change it.

It gives you power to create public/private variables/methods , and avoids polluting global scope . Private methods are anything you don’t want users/devs/hackers to be able to see/call outside the scope they’re in. We might be making server calls and posting sensitive data, we don’t want to expose those functions publicly, they could post anything back then and take advantage of our code.

General Revealing Module Pattern Structure

Simplified JavaScript Jargon is a community-driven attempt at explaining the loads of buzzwords making the current JavaScript ecosystem in a few simple words. The idea is not to replace individual documentations, but to act as some kind of glossary that can be easily referenced. If you’re interested in additional information about structuring JavaScript code check out my Pluralsight course. Demos of all the patterns covered in this series can be downloaded below.

The central principle of the Revealing Module pattern is that all functionality and variables should be hidden unless deliberately exposed. You can use double underscore prefix for event binding function, to separate it from private functions. You may have noticed the _ before our private methods and properties. Because JavaScript does not have a private keyword its common to prefix private properties with an underscore. This basically assigns the module to a variable that we can use to call our modules methods.

Just like the module pattern, any functions that are defined inside of the module container will be duplicated in memory every time you create a new instance of the module. To be fair, this is probably not that big of a deal anyway. As getify so eloquently states in his You Don’t Know JavaScript series, the optimization engine in JavaScript can handle this with no problems.

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. 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.

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I created a revealing module pattern with following code. 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. Public members are defined in the return object literal. What if we could combine this pattern with the Prototype Pattern though to get the benefits provided by prototyping? The core aspect of the Revealing Module Pattern is the use of a closure which returns the public interface for the API.

  • But we can’t fiddle with our songList or access the loadSong() method.
  • Consider your method switching between an online or offline service call or if param2 was passed in you want to make sure diaryModule.somethingElse received the right config object.
  • 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.
  • These shown methods would be embedded inside the bigger method which is the main method visible to the user, which will function at first itself.

As a quick review, I showed the following code in the first post since it shows “function spaghetti code” and illustrates code that can be encapsulated into a more re-useable object. The code simply lists all functions directly with no encapsulation and defines several global variables. While the code works fine this way, I’ll examine how we can restructure it to follow the 20 Recipes for Programming MVC 3.

The Revealing Module Pattern in Javascript

Closures are often considered a complex subject in Javascript and may be difficult to understand for beginner developers. You can invoke the function ‘callAddPrpertyFn’ from outside the IIFE function as shown below. Hate the complexity of modern front‑end web development?

As you can see, this isn’t a radically changed version. It has the same smell, but is just structured a bit differently. Note that all of the real logic is in private functions.

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