Simplified GoogleCodeJam Javascript stdio tokenizer

Solution.js

'use strict';
// Does not work on Google's servers, try stdio-async instead
const fs = require('fs');

let tok = (function () {
  let buffer = Buffer.alloc(1);
  function getc() {
    while (true) {
      try {
        let bytes_read = fs.readSync(process.stdin.fd, buffer, 0, 1);
        if (bytes_read) {
          return buffer.toString();
        } else {
          return null;
        }
      } catch (e) {
        if (e.code !== 'EAGAIN') {
          throw e;
        }
        // this exception happens when exhausting the buffer on Linux, with e.code === 'EAGAIN',
        //   just retry, and that's fine
        // However, only on Google CodeJam servers, only on the interactive problems, it
        // then *never* reads any data after that.
      }
    }
  }
  return function () {
    let c;
    // skip past initial whitespace
    while ((c = getc()) <= ' ') {}
    let r = [c];
    do {
      c = getc();
      if (!c || c <= ' ') {
        return r.join('');
      }
      r.push(c);
    } while (true);
  };
}());

tok(); // N
tok(); // A
console.log('2 2');
tok(); // x // Never returns!
tok(); // y