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.