How to use Filter, Map and Find method in Node js

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Let us look into how to use Map, Filter, and Find method in Node JS. All these are higher-order functions. In JavaScript, the purpose of using arrays is to access Data or manipulate Data and call multiple functions using a single code. An Array is a single variable that is used to store different elements in the Databases, at the same time retrieve the data as a single variable.

For example;  if we query a database we will most likely get the rows as an array of objects. Where each object represents a row in the database.

Here the purpose of using JavaScript as a programming language by most of the top Web App Development Company in Chennai is, JavaScript function allows you to define a block of code, give it a common name and execute it whenever required.  

What is Higher Order Function?

Map, Filter and Reduce are called higher-order functions, they are the part of Javascript array prototype and it has to be called directly on an array. A higher-order function is a function that takes one or more “functions as arguments’ ‘ or returns a function as its result. 

What is Node JS?

Node js is a back-end JavaScript runtime environment, which runs on the v8 engine. To learn the node js – javascript is the fundamental coding language for it. The standardization for this language is called ECMAScript, now the current edition is ES6. The very basics and most used concepts in nodejs are

  • filter()
  • map()
  • find()

At Lia Infraservices – Leading Web App Development Company in Chennai, we develop fast and scalable web servers using Javascript as event-driven programs that use call back functions to complete an action. 

How to use Filter, Map and Find method in Node js:

We will see one by one with examples:

1. How to use Filter method in Node Js

This filter method used to filter the array of elements with specific conditions, and reproduce the new array with the conditions

For example: 

I have one array, it contains 7 names, and now I need an array with some conditions like the length of the name should be less than 4 characters. So if I am using the filter method here I can get the new array of names with the specified conditions, which is the length of a name less than 4.

The below image contains the example with the simple node application

2. How to use Map Method in Node JS :

The map method is used to change the values in a specific array or find the number of elements in an array with the specified conditions. It iterates the elements in the array and applies the condition on that, and returns only ‘true’ or ‘false’ in the new array.


The same above array I will take, now I applied the condition that I need to know how many names in that array is greater than 4 letters. So now it should give 4 names from that array. So the return array will have 4 true values and 3 false values.

The below image contains the above example

3. How to use Find Method in Node JS:

Find method used to find a specific or single element from the array. It gives only one value as a return. If we want we can make it true or false or we will get the value itself.

For example 

I take the above array and it contains a set of name lists, now I want to take the single name from that I can do. For that, we will use the find() method. Now I want “Deva” from that array so I can take it.

The below image contains the example with a simple node application


The constant emerging technologies in the world of web app development always keep the emerging technology trend evolving.

Contact Lia Infraservices the leading Mobile App Development Company in Chennai helps you with how to use the console filter, map and find in Javascript.

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