nodejs synchronization read large file line by line?

For large files, readFileSync can be inconvenient, as it loads the whole file in memory. A different synchronous approach is to iteratively call readSync, reading small bits of data at a time, and processing the lines as they come. The following bit of code implements this approach and synchronously processes one line at a time from the file 'test.txt':

var fs = require('fs');var filename = 'test.txt'var fd = fs.openSync(filename, 'r');var bufferSize = 1024;var buffer = new Buffer(bufferSize);var leftOver = '';var read, line, idxStart, idx;while ((read = fs.readSync(fd, buffer, 0, bufferSize, null)) !== 0) {  leftOver += buffer.toString('utf8', 0, read);  idxStart = 0  while ((idx = leftOver.indexOf("\n", idxStart)) !== -1) {    line = leftOver.substring(idxStart, idx);    console.log("one line read: " + line);    idxStart = idx + 1;  }  leftOver = leftOver.substring(idxStart);}

use https://github.com/nacholibre/node-readlines

var lineByLine = require('n-readlines');var liner = new lineByLine('./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');

Use readFileSync:

fs.readFileSync(filename, [encoding]) Synchronous version of fs.readFile. Returns the contents of the filename.

If encoding is specified then this function returns a string. Otherwise it returns a buffer.

On a side note, since you are using node, I'd recommend using asynchronous functions.