How to read from stdin line by line in Node

node.js, stdin

Solution

You can use the readline module to read from stdin line by line:

const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

rl.on('line', (line) => {
    console.log(line);
});

rl.once('close', () => {
     // end of input
 });

Problem

I'm looking to process a text file with node using a command line call like: `node app.js < input.txt` Each line of the file needs to be processed individually, but once processed the input line can be forgotten. Using the on-data listener of the stdin, I get the input steam chunked by a byte size so I set this up. ``` process.stdin.resume(); process.stdin.setEncoding('utf8'); var lingeringLine = ""; process.stdin.on('data', function(chunk) { lines = chunk.split("\n"); lines[0] = lingeringLine + lines[0]; lingeringLine = lines.pop(); lines.forEach(processLine); }); process.stdin.on('end', function() { processLine(lingeringLine); }); ``` But this seems so sloppy. Having to massage around the first and last items of the lines array. Is there not a more elegant way to do this?

Original source

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