Till recently I've used this way (this demo script reads and outputs itself line by line):
const fs = require('fs');
const rl = require('readline');
let lineNumber = 0;
rl.createInterface({
input: fs.createReadStream(__filename, { encoding: 'utf8' }),
}).on('line', line => {
if (++lineNumber === 1) line = line.replace(/^\uFEFF/, '');
console.log(line);
}).on('close', () => {
console.log('EOF');
});However, it makes me uneasy that each iteration except the first one should increment and compare the lineNumber in vain. So I've come to this solution:
const fs = require('fs');
const rl = require('readline');
const input = fs.createReadStream(__filename, { encoding: 'utf8' });
input.once('readable', () => {
const maybeBOM = input.read(1);
if (maybeBOM !== '\uFEFF') input.unshift(maybeBOM);
rl.createInterface({
input,
}).on('line', line => {
console.log(line);
}).on('close', () => {
console.log('EOF');
});
});However, now I doubt if this flow is reliable. Could it somehow mess up the stream internal mechanics? Is this sequence of stream modes and methods safe?
Till recently I've used this way (this demo script reads and outputs itself line by line):
However, it makes me uneasy that each iteration except the first one should increment and compare the
lineNumberin vain. So I've come to this solution:However, now I doubt if this flow is reliable. Could it somehow mess up the stream internal mechanics? Is this sequence of stream modes and methods safe?