Node.js is JavaScript running on the server. It is an open-source, cross-platform, back-end JavaScript runtime environment that executes JavaScript code outside a web browser.

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What Is a Function?

A function is a logical set of statements summoned to get the desired result or perform a specific action. 

Functions in Node.js are used directly in the code. Using Node.js functions enables you to get the desired action of your app in a single process, i.e., you don't have to create a new thread for every new request. 

Function Scope

A new variable scope gets created whenever you call a function.

It raises two different scenarios: 

  • Any variable declared in the parent scope can be accessed anywhere in that function.

  • When the function exits, variables declared within the new scope become unavailable.

Consider the below sample code:


Code Output: 

Following is the output you will get when the above code runs: 



Combining scoping with anonymous functions is a better way to use private variables; the variables disappear when you exit the anonymous function.

Create New Node.js Function 

Creating functions in Node.js is not different from creating processes in JavaScript. You can create a new Node.js function to get the desired output by following the steps discussed below. 

1. First, you have to click on the Workflows option from your Node.js main window. It will navigate you to your Workflow Dashboard.

2. From the upper taskbar, click on the Functions tab.

3. Post this, a new page will pop up, from where you have to click on the New Function button. A create page will appear asking for required inputs.

4. Now, enter a Function Name; remember that this name will be the identifier to invoke the function. Make sure the function name has no empty spaces and should be meaningful.

5. In the language choice, select Node.js for scripting your function.


6. As per your requirement, specify the Arguments.

7. Click on the Create Function button; clicking this will bring the builder to your screen. 

8. Lastly, you need to add the required Node.js code to your created function.

To check if your function is created or not, visit the Functions section in the workflow dashboard.

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Arguments and Parameters 

Arguments and Parameters are among the essential parts of a function. Arguments are the instances passed to the method, and Parameters are the variables assigned to store value for the arguments. 

You can specify an argument directly along with the Node.js function during function creation.

But, what if there is a requirement to add more arguments? If you want to add more arguments for the same function, you can easily do so using the FunctionProperties option available on the builder page. 

It's important to define parameters used in the Node.js functions before running your program. 

If you find the parameter to be confusing, remember it's like a container that receives the argument value after getting passed from the deluge.

Sample Function

Node.js has different functions for different uses like any other programming language, for example, Sample Function. You can create Sample Function whenever you find the necessity to calculate the average in Node.js.



Sample Function, when implemented, uses deluge and receives values obtained to update records.

Call a Node.js Function

Calling a function in Node.js is quite similar to calling a function in Java.

Check out the statement in the code below to call a Node.js function in a deluge script. 


In this example, the Node.js function “thisapp.calculatorFunction(total,count);” contains the total value as a collection and prints when called.

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Get Value

The Get Value Node.js function assigns variables to the parameters (Parameters that you input in the arguments to obtain your desired output). 

The two parameters used in the above code, Total (Grand Total) and Count (Number of Subjects), can be easily obtained using the command statement basicIO.getParameter. 


To upload the .js format file, you need to use the node_modules folder. You can directly use this folder in your Node.js functions code. 

The folder allows you to create the code and save it. Also, you can directly use your Node.js function whenever you need to access this code.

Key Notes: 

  • Return Type: A Node.js function always gives a Collection data type value in return. 
  • Namespace: Node.js has a default Namespace: "Namespace".
  • Argument: Always use string argument in Node.js functions because it accepts only string values.
  • You cannot rename your Node.js functions it is created.

Learn More About Node.js Today!

Ryan Dahl introduced Node.js in 2009. This function can be used to build scalable network applications such as command-line applications, web applications, real-time chat applications, REST API servers, etc. Node.js is widely used for building network programs like web servers, similar to PHP, Java, or ASP.NET.

Node.js is only a part of the entire web development curriculum. Several other web development-related topics have been discussed in detail in our Post Graduate Program in Full Stack Web Development course. Enrolling in this program will help you learn modern coding techniques in just a few months. 

You can also pursue several SkillUp Courses on web development offered by Simplilearn to enhance your skills as a Web Developer. But, why SkillUp? In this current scenario where every platform claims to have the best course material, having a "Why to choose this?" question in mind is a given. Well, SkillUp is a free platform with a 24/7 expert portal available for all your doubts and queries. Do check it out and learn the most relevant courses for FREE! 

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