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JavaScript Read Text File Line By Line

Last Updated : Mar 11, 2024

JavaScript Read Text File Line By Line

In this article we will show you the solution of JavaScript read text file line by line, we can read big files without completely storing them to memory thanks to the ability to read files line by line.

Now move to the reading the text file line by line.

Step By Step Guide On JavaScript Read Text File Line By Line :-

It helps the application run more efficiently while saving resources. It enables us to search for the necessary data, and once the pertinent data is located, we may halt the search process and reduce unauthorized memory usage.

Any website that interacts with its users must be able to read files through a browser.

Without keeping the file online, it can still be accessed. To read a file, JavaScript offers a built-in function called FileReader().

A JavaScript file can also be read using a variety of NPM modules. This article demonstrates multiple JavaScript ways for line-by-line file reading.

How Does JavaScript Read a File Line by Line?

JavaScript is renowned for offering a wide range of properties and methods to make things easier for the user. Each line of a file's content can be read using the built-in FileReader() function.

For instance, the file can be accessed and read line by line using the "readline" module. Additionally, people can access the file through local computers or internet.

Using the Readline Module and Line-Reader Module, we will reach the goal.

Method 1: Using Readline Module:

The Readline module, a native JS module, was created specifically for reading material line by line from any readable stream. From the command line, data can be read using it.

Method 2: Using the FileReader() Method:

In this, HTML and JavaScript code are used to demonstrate how to use the FileReader() method to read a file line by line while utilising JavaScript’s features.


Hello, everyone…
This is our demo example which shows you how to read text file line by line in JavaScript.


console.log("Welcome to Talkerscode");
const f = require('fs');
const readline = require('readline');
var user_file = './demo.txt';
var r = readline.createInterface({
    input : f.createReadStream(user_file)
r.on('line', function (text) {
  1. Firstly, we create the text file which is used in js code.
  2. In the first line of js code we print the statement Welcome to Talkerscode with the help of console.log.
  3. Then with the help of const keyword we use the require(“readline”) is employed to read a data stream from a file.
  4. After that the “user file” variable is then given the value “./JavaScript.txt”.
  5. Then we use the readline it is a readline.createInterface provides an interface for the readline module to read the content of a file.
  6. Then we pass the value “text” is passed to a callback.
  7. After that we print the text which is in our text file using console.log.

Conclusion :-

Hence, we have successfully learnt about the concept of reading text file line by line in javascript.

Also, we learnt that To read a file line by line in JavaScript, use the readline module and the built-in method FileReader().

The local system's files can have their contents read using the FileReader() method. Additionally, the material is read using the readline module.

The file's source is necessary for both of these techniques.

I hope this article on JavaScript read text file line by line helps you and the steps and method mentioned above are easy to follow and implement.

Author Image About Dikshita

Passionate Electronics and Communication Engineering student with expertise in web development (HTML, CSS, JS,PHP, Bootstrap, React.js) and content writing. Eager problem solver and tech enthusiast, adept at creating engaging web experiences.

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