n-readlines-next

Read file line by line without buffering the whole file in memory.

Usage no npm install needed!

<script type="module">
  import nReadlinesNext from 'https://cdn.skypack.dev/n-readlines-next';
</script>

README

Build Status

node-readlines-next

Fork

node-readlines-next is a fork of node-readlines! A package developed by Yoan Arnaudov! Original Repo here

The author wasn't active for 2 years up to now!

I took the deliberate to Fork it! Merged one PR (One bring better performance) [check here]! And added typescript declarations!

Also if any PR are send! I'll make sure to treat them!

Original author description

Reading file line by line may seem like a trivial problem, but in node, there is no straightforward way to do it. There are a lot of libraries using Transform Streams to achieve it, but it seems like a overkill, so I've wrote simple version using only the filesystem module of node. Note that this is synchronous library.

Install with npm install n-readlines-next


Documentation

new readlines(filename, [options]);

new readlines(fd, [options]);

Arguments

  • filename - String path to the file you want to read from
  • fd - File descriptor
  • options - Object
    • readChunk - Integer number of bytes to read at once. Default: 1024
    • newLineCharacter - String new line character, only works with one byte characters for now. Default: \n which is 0x0a hex encoded

node-readlines can handle files without newLineCharacter after the last line


readlines.next()

Returns buffer with the line data without the newLineCharacter or false if end of file is reached.


readlines.reset()

Resets the pointer and starts from the beginning of the file. This works only if the end is not reached.


Example

var ReadLines = require('n-readlines');
var liner = new ReadLines('./textFile.txt');

var line;
var lineNumber = 0;
while (line = liner.next()) {
    console.log('Line ' + lineNumber + ': ' + line.toString('ascii'));
    lineNumber++;
}

console.log('end of line reached');

Typescript

For imports and types

import LineReader, { ReadLinesOptions } from 'n-readlines-next';
export class CsvReader {
  private _lineReader: LineReader;
}