gistfile1.js

const os = require('os');
const fs = require('fs');
const path = require('path');
const execFile = require('child_process').execFile;

const tmpfile = path.join(os.tmpdir(), process.versions.v8+'.flags.json');
const exclusions = ['--help'];

module.exports = function (cb) {
  fs.exists(tmpfile, function (exists) {
    if (exists) {
      cb(null, require(tmpfile));
    } else {
      execFile(process.execPath, ['--v8-options'], function (execErr, result) {
        var flags;
        if (execErr) {
          return cb(execErr);
        }
        flags = result.match(/\s\s--(\w+)/gm).map(function (match) {
          return match.substring(2);
        }).filter(function (name) {
          return exclusions.indexOf(name) === -1;
        });
        fs.writeFile(tmpfile, JSON.stringify(flags), { encoding:'utf8' },
          function (writeErr) {
            if (writeErr) {
              return cb(writeErr);
            }
            cb(null, flags);
          }
        );
      });
    }
  });
};