Why does `global.require` return undefined when executed as nodejs script?

Question

If I log global.require by piping script to node, it is a function, but if I run from within script passed to node, it is undefined...

➜  Desktop  cat req.js 
console.log(global.require)
➜  Desktop  cat req.js | node
{ [Function: require]
  resolve: [Function],
  main: undefined,
  extensions: 
   { '.js': [Function],
     '.json': [Function],
     '.node': [Function: dlopen] },
  registerExtension: [Function],
  cache: {} }
➜  Desktop  node req.js 
undefined
➜  Desktop

Have I found Schrödinger's variable - or is there a more mundane explanation?

I just tried with `console.log(require)` and it works. Must be something to do with accessing `root`? — JosephGarrone, Jan 02 '16 at 13:23
@Amit http://stackoverflow.com/questions/21578446/what-is-the-root-object-in-node-js — robertklep, Jan 02 '16 at 13:36
Can you reproduce this without `root`? What about `global.require`? — Amit, Jan 02 '16 at 13:45

robertklep · Answer 1 · 2016-01-02T14:01:55.280

5

If I understand the Node code correctly:

When Node starts up, there's a few different execution paths that Node can take. In your case, there are two: reading the script from stdin, or reading it from file.

reading from stdin will execute this code, which, as you can see here, will define global.require;
reading from a file will follow a different code path (starting here) that doesn't define global.require;

Perhaps in the latter case, require is provided by the module context and hence it's not necessary to be added to global, but that's just me guessing.

edited Jan 02 '16 at 14:01

answered Jan 02 '16 at 13:55

robertklep

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I took a different path trying to figure this out, and I found your missing piece [here](https://nodejs.org/api/globals.html#globals_require) - `require` does come from the module context. – Amit Jan 02 '16 at 14:01

Why does `global.require` return undefined when executed as nodejs script?

1 Answers1