CODEWITHSUNDEEP
javascriptnode.jsecmascript-6babeljs
Dave Thomas
Dave Thomas

Reputation: 425

os.hostname() is empty after transpiling through babel

So, I'm writing a server side app in ES6/node. Below is the offending code. I know that's not ES6, but other parts of the app are (and ideally, I'd be using ES6's import - I only fell back to require because I wanted to test the raw code in node itself without the need for transpiling.

var os = require("os");
var hostname = os.hostname();
console.log(hostname);

So, if I have a JavaScript file called, say, test.js, with that code in it... Then I throw that at node I get the correct hostname printed on the console.

But if I run it through babel, when I run it, I get nothing. No output at all.

Interestingly enough, if I add this line to the code:

console.log(os)

then the raw JS gives me this output:

{ hostname: [Function: getHostname],
  uptime: [Function: getUptime],
  freemem: [Function: getFreeMem],
  totalmem: [Function: getTotalMem],
  cpus: [Function: getCPUs],
  type: [Function: getOSType],
  release: [Function: getOSRelease],
  networkInterfaces: [Function: getInterfaceAddresses],
  homedir: [Function: getHomeDirectory],
  userInfo: [Function: getUserInfo],
  loadavg: [Function: loadavg],
  constants:
   { UV_UDP_REUSEADDR: 4,
     errno:
      { E2BIG: 7,
        EACCES: 13,
        EADDRINUSE: 98,
        EADDRNOTAVAIL: 99,
        EAFNOSUPPORT: 97,
        EAGAIN: 11,
        EALREADY: 114,
        EBADF: 9,
        EBADMSG: 74,
        EBUSY: 16,
        ECANCELED: 125,
        ECHILD: 10,
        ECONNABORTED: 103,
        ECONNREFUSED: 111,
        ECONNRESET: 104,
        EDEADLK: 35,
        EDESTADDRREQ: 89,
        EDOM: 33,
        EDQUOT: 122,
        EEXIST: 17,
        EFAULT: 14,
        EFBIG: 27,
        EHOSTUNREACH: 113,
        EIDRM: 43,
        EILSEQ: 84,
        EINPROGRESS: 115,
        EINTR: 4,
        EINVAL: 22,
        EIO: 5,
        EISCONN: 106,
        EISDIR: 21,
        ELOOP: 40,
        EMFILE: 24,
        EMLINK: 31,
        EMSGSIZE: 90,
        EMULTIHOP: 72,
        ENAMETOOLONG: 36,
        ENETDOWN: 100,
        ENETRESET: 102,
        ENETUNREACH: 101,
        ENFILE: 23,
        ENOBUFS: 105,
        ENODATA: 61,
        ENODEV: 19,
        ENOENT: 2,
        ENOEXEC: 8,
        ENOLCK: 37,
        ENOLINK: 67,
        ENOMEM: 12,
        ENOMSG: 42,
        ENOPROTOOPT: 92,
        ENOSPC: 28,
        ENOSR: 63,
        ENOSTR: 60,
        ENOSYS: 38,
        ENOTCONN: 107,
        ENOTDIR: 20,
        ENOTEMPTY: 39,
        ENOTSOCK: 88,
        ENOTSUP: 95,
        ENOTTY: 25,
        ENXIO: 6,
        EOPNOTSUPP: 95,
        EOVERFLOW: 75,
        EPERM: 1,
        EPIPE: 32,
        EPROTO: 71,
        EPROTONOSUPPORT: 93,
        EPROTOTYPE: 91,
        ERANGE: 34,
        EROFS: 30,
        ESPIPE: 29,
        ESRCH: 3,
        ESTALE: 116,
        ETIME: 62,
        ETIMEDOUT: 110,
        ETXTBSY: 26,
        EWOULDBLOCK: 11,
        EXDEV: 18 },
     signals:
      { SIGHUP: 1,
        SIGINT: 2,
        SIGQUIT: 3,
        SIGILL: 4,
        SIGTRAP: 5,
        SIGABRT: 6,
        SIGIOT: 6,
        SIGBUS: 7,
        SIGFPE: 8,
        SIGKILL: 9,
        SIGUSR1: 10,
        SIGSEGV: 11,
        SIGUSR2: 12,
        SIGPIPE: 13,
        SIGALRM: 14,
        SIGTERM: 15,
        SIGCHLD: 17,
        SIGSTKFLT: 16,
        SIGCONT: 18,
        SIGSTOP: 19,
        SIGTSTP: 20,
        SIGTTIN: 21,
        SIGTTOU: 22,
        SIGURG: 23,
        SIGXCPU: 24,
        SIGXFSZ: 25,
        SIGVTALRM: 26,
        SIGPROF: 27,
        SIGWINCH: 28,
        SIGIO: 29,
        SIGPOLL: 29,
        SIGPWR: 30,
        SIGSYS: 31,
        SIGUNUSED: 31 } },
  arch: [Function],
  platform: [Function],
  tmpdir: [Function],
  tmpDir: [Function],
  getNetworkInterfaces: [Function: deprecated],
  EOL: '\n',
  endianness: [Function] }

And the transpiled code gives me this output

{ endianness: [Function],
  hostname: [Function],
  loadavg: [Function],
  uptime: [Function],
  freemem: [Function],
  totalmem: [Function],
  cpus: [Function],
  type: [Function],
  release: [Function],
  getNetworkInterfaces: [Function],
  networkInterfaces: [Function],
  arch: [Function],
  platform: [Function],
  tmpDir: [Function],
  tmpdir: [Function],
  EOL: '\n' }

I downloaded the and installed the babel plugin "transform-inline-environment-variables" and my .babelrc contains the line

"plugins": ["transform-inline-environment-variables"]

But that doesn't seem to have done anything. What am I doing wrong? This app needs to know what host it's running on - It may run on different hosts, and will need to do different things based on the name of the host.

Any help gratefully received. This is my first foray into server side JavaScript.

As requested, the transpiled code:

!function(n){function t(e){if(r[e])return r[e].exports;var o=r[e]={i:e,l:!1,exports:{}};return n[e].call(o.exports,o,o.exports,t),o.l=!0,o.exports}var r={};t.m=n,t.c=r,t.i=function(n){return n},t.d=function(n,r,e){t.o(n,r)||Object.defineProperty(n,r,{configurable:!1,enumerable:!0,get:e})},t.n=function(n){var r=n&&n.__esModule?function(){return n.default}:function(){return n};return t.d(r,"a",r),r},t.o=function(n,t){return Object.prototype.hasOwnProperty.call(n,t)},t.p="",t(t.s=1)}([function(n,t,r){"use strict";t.endianness=function(){return"LE"},t.hostname=function(){return"undefined"!=typeof location?location.hostname:""},t.loadavg=function(){return[]},t.uptime=function(){return 0},t.freemem=function(){return Number.MAX_VALUE},t.totalmem=function(){return Number.MAX_VALUE},t.cpus=function(){return[]},t.type=function(){return"Browser"},t.release=function(){return"undefined"!=typeof navigator?navigator.appVersion:""},t.networkInterfaces=t.getNetworkInterfaces=function(){return{}},t.arch=function(){return"javascript"},t.platform=function(){return"browser"},t.tmpdir=t.tmpDir=function(){return"/tmp"},t.EOL="\n"},function(n,t,r){"use strict";var e=r(0),o=e.hostname();console.log(e),console.log(o)}]);

That all looks very scary to me. I've been writing JavaScript since it was LiveScript in 1995 and babel's output has always completely baffled me, LOL.

Upvotes: 0

Views: 807

Answers (1)

Dave Thomas
Dave Thomas

Reputation: 425

Turns out, it was the webpack config that was causing the problem. Jaromanda X noticed that the transpiled code was targetting the browser instead of node, and a quick google search brought up this SO question: Webpack babel config for both server and client javascript?

So the solution (in the answer to that question) is simply to add a line to the webpack config:

target: 'node'

Upvotes: 0

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