n-readlines2

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

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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

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readlines.next()

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

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readlines.reset()

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

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readlines.close()

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

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Example

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

let line;
let lineNumber = 0;

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

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