HackerRank Javascript stdin using an ES6 generator

hackerrank.js

'use strict';

function* Lines( stream ) {
    const EOL   = require('os').EOL;
    const Fs    = require('fs');
    const buf   = new Buffer(1);

    while( true ) {
        const chars = [];
        while (Fs.readSync(stream.fd, buf, 0, buf.length)) {
            let str = buf.toString();
            if (str === EOL) { break; }
            chars.push( str );
        }

        if (chars.length < 1) { break; }
        yield chars.join('');
    }
}

const lines = Lines( process.stdin );
for (let T = 0, end = parseInt( lines.next().value ); T < end; T++) {
    let N   = parseInt( lines.next().value );

    // Do your work here (or replace this loop entirely)
    console.log("%d", N);
}