A nodejs REPL that'll autoload code

fnode.js

#!/usr/bin/env node

// save somewhere in $PATH as fnode, remember to chmod +x

const vm = require('vm');
const fs = require('fs');
const tty = require('tty');
const path = require('path');
const repl = require('repl');

const homedir = require('os').homedir();
const startup = path.join(homedir, '.fnode.js');

const start = function(input, code) {
  const init = function(context) { vm.runInContext(code, context); }

  const r = repl.start({
    breakEvalOnSigint: true,
    prompt: '> ',
    input: input,
    // if input is set but output isn't things break
    output: process.stdout
  });

  // FIXME Windows support?
  if (process.env['NODE_REPL_HISTORY'] !== '') {
    let hist = process.env['NODE_REPL_HISTORY'] || path.join(homedir, '.node_repl_history');
    r.setupHistory(hist, function(){});
  }

  // re-run the init code if the session is reset
  r.on('reset', init);

  // without this, sometimes one needs to press enter after Ctrl-D to exit.
  r.on('exit', function(){ process.exit(0); });

  init(r.context);
}

const readFiles = function(i) {
  let fileName;

  if (i == 1) {
    if (fs.existsSync(startup)) {
      fileName = startup;
    } else {
      readFiles(2);
    }
  } else if (i < process.argv.length) {
    fileName = process.argv[i];
  } else {
    console.log('Welcome to Node.js '+process.version+' ('+process.argv[0]+')');
    return start(replInput, code);
  }

  fs.readFile(fileName, function(err, data) {
    if (err) throw err;
    code += ';\n' + data.toString();
    readFiles(i+1);
  });
}

let code = '', replInput = process.stdin;

// If stdin is a pipe, open the tty to read commands, and read
// startup code from stdin
if (!Boolean(process.stdin.isTTY)) {
  replInput = tty.ReadStream(fs.openSync('/dev/tty', 'r'));
  //replInput.setRawMode(false);

  let buf = Buffer.alloc(0);
  process.stdin.on('data', function(data){
    buf = Buffer.concat([buf, data]);
  });
  process.stdin.on('end', function() {
    code += ';\n' + buf.toString();
    readFiles(1);
  });
} else {
  readFiles(1);
}