node-readlines

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

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.

readlines.close()

Manually close the open file, subsequent next() calls will return false. This works only if the end is not reached.

Example

const lineByLine = require('n-readlines');
const liner = new lineByLine('./test/fixtures/normalFile.txt');

let line;
let lineNumber = 0;

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

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