Let's first take a look at what the module object is all about. Nowadays there are a lot of open source libraries that you can use within your projects. By clicking “Sign up for GitHub”, you agree to our terms of service and To illustrate what I mean, let’s change the code in index.js to log the value of module: As you can see, module has an exports property.

It doesn’t have to be the same as the original variable name.

By the end of this article, you should be comfortable not only using the syntax, but also understanding what it actually does under the hood. Well, whether if this is the right way to do it is not the absolute truth, but a lot of libraries rely on the Event Emitter class of Node.js. var eventEmitter = new events.EventEmitter(); eventEmitter.on('scream', function() console.log('A scream is detected! Now, import this message module and use it as shown below. In fact many node modules such as fs.readstream emits event when it is done with reading file. Okay, by now you’re probably thinking, Why does all this talk of different modules matter? A question I get a lot is this: “If we import the same module in two files, will we get the same object reference?” In short, yes. All objects that emit events are instances of the EventEmitter class, these objects expose an eventEmitter.on() function that allows one or more functions to be attached to named events emitted by the object. GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together.

(Don’t worry, we’ll cover importing code in the next section.). Also notice that in the require statement, the module name is prefixed with ./, as it’s a local file. Chaining asynchronous actions in JavaScript can take a bit of time to get used to. Google, Netflix and ILM are Python users. All objects that emit events are instances of the EventEmitter class. Run the above example and see the result, as shown below. https://www.sitepoint.com/understanding-module-exports-exports-node-js The module.exports is a special object which is included in every JavaScript file in the Node.js application by default. Created a class named mobileEvents extended from core EventEmitter. You are probably just copy and pasting the source somewhere instead of using the required require statement as illustrated in the README of this project. Did you notice it has an exports property? You signed in with another tab or window.

The best way to understand the module system is to see how it’s evolved over time, and why.

Remember: Module.exports is simply an object that you assign properties to, and that object gets passed to your requiring file. To round it all off, we’ll go through some best practices for using module exporting to break down and give your application some great structure.

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