Require in nodejs

Question

The argument of require(...) in node.js is a filename. If I had a module source code in a string code, could I somehow call require(code) and load functions from that string?

Answer 1

I put this into a function for reuse. It creates a file in the os temp directory based on a random hash, requires it and then deletes it.

var fs     = require('fs'),
    os     = require('os'),
    crypto = require('crypto');

function requireString(moduleString) {
  var token           = crypto.randomBytes(20).toString('hex'),
      filename        = os.tmpdir() + '/' + token + '.js',
      requiredModule  = false;

  // write, require, delete
  fs.writeFileSync(filename, moduleString);
  requiredModule = require(filename);
  fs.unlinkSync(filename);

  return requiredModule;
}

Then you can do:

var carString = "exports.start = function(){ console.log('start'); };",
    car       = requireString(carString);

console.log("Car:", car);

This is still more of a workaround, but more convenient to use, I think.

Answer 2

A work around could be to write the module source code to a temporary file ./tmp-file.js and then require('./tmp-file'), and then remove the file.

This is probably not optimal because you would either have to block and write the file synchronously, or put everything requiring that module in the callback to the async write.

A working example for async file write (gist - also includes sync file write):

var http = require('http');
var fs = require('fs');

var helloModuleString = "exports.world = function() { return 'Hello World\\n'; }";
fs.writeFile('./hello.js', helloModuleString, function (err) {
  if (err) return console.log(err);
  var hello = require('./hello');

  http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end(hello.world());
  }).listen(1337, '127.0.0.1');

  console.log('Server running at http://127.0.0.1:1337/');
});

Results in:

$ curl 127.0.0.1:1337
> Hello World