linecounter2

⚡ Fastest and memory-efficient async file line counter with customizable buffer size and separator.

Allow you to count the lines of a huge file by reading chunk by chunk without buffering the whole file in memory. Has the ability to customize a line separator (multiple characters allowed), and skip blank lines.

• Fast & memory-efficient.
• Well-tested with Jest.
• Written in TypeScript.
• CLI supported.

Install

# using npm
npm install linecounter2
# using yarn
yarn add linecounter2

Usage

Import

// in ESM
import { LineCounter } from 'linecounter2';
// in CommonJS
const { LineCounter } = require('linecounter2');

Example

const total = await LineCounter.count({ filePath: './file.txt' });
console.log(total);

API

LineCounter.count(options: LineCounterOptions): Promise<number>

It returns the total lines in the file. The options you can pass are:

Name	Type	Default	Description
filePath	string	none	The path or location of your file (required)
bufferSize	number	65536	Chunk/buffer size in bytes. Default: 64 KB
lineSeparator	string	none	Separator to separate between lines (multiple characters allowed). Will be automatically determined between '\r\n', '\n', or '\r'
skipBlank	boolean	false	Used to skip blank lines (including whitespace lines)
skipEndingLineBreak	boolean	false	Used to skip the last blank line (if any) of the file. See the example below

Example:

const filePath = './file.txt';

const total1 = await LineCounter.count({ filePath });
console.log('total lines =', total1);

const total2 = await LineCounter.count({ filePath, skipBlank: true });
console.log('total lines [skip blank] =', total2);

const total3 = await LineCounter.count({ filePath, skipEndingLineBreak: true });
console.log('total lines [skip ending line break] =', total3);

./file.txt

1111
2222
3333

5555
6666
7777
8888
9999

NOTE: there is a blank line at the end of the above file (after the 9999 line) which may not be visible.

Output:

total lines = 10
total lines [skip blank] = 8
total lines [skip ending line break] = 9

CLI

This library supports CLI in an easy way.

Example:

# using npm
npx linecounter2 ./file.txt
# using yarn
yarn linecounter2 ./file.txt

./file.txt

1111
2222
3333

5555

Output:

5

You can pass additional options as arguments as follows:

# using npm
npx linecounter2 ./file.txt --skipBlank --bufferSize=1024 --lineSeparator=\\n
# using yarn
yarn linecounter2 ./file.txt --skipBlank --bufferSize=1024 --lineSeparator=\\n

Output:

4

Testing

This library is well tested. You can test the code as follows:

# using npm
npm test
# using yarn
yarn test

Related

• chunkreader2 - Asynchronous, buffered, chunk-by-chunk file reader with customizable buffer size.
• linereader2 - Asynchronous, buffered, line-by-line file reader with customizable buffer size and separator. (This library uses this package internally)

Contribute

If you have anything to contribute, or functionality that you lack - you are more than welcome to participate in this!

License

Feel free to use this library under the conditions of the MIT license.