What's the difference when passing the reference of require to runInContext and not?

In docs of vm module, is an example of Running an http server within a vm:

'use strict';
const vm = require('vm');

let code =
`(function(require) {

   const http = require('http');

   http.createServer( (request, response) => {
     response.writeHead(200, {'Content-Type': 'text/plain'});
     response.end('Hello World\\n');
   }).listen(8124);

   console.log('Server running at http://127.0.0.1:8124/');
 })`;

 vm.runInThisContext(code)(require);

I am wondering why should we pass the require to the code inside the context? Is there a specific reason? In fact, I tried the following in node 6.10:

'use strict';
const vm = require('vm');

let code =
`(function() {

   const http = require('http');

   http.createServer( (request, response) => {
     response.writeHead(200, {'Content-Type': 'text/plain'});
     response.end('Hello World\\n');
   }).listen(8124);

   console.log('Server running at http://127.0.0.1:8124/');
 })`;

 vm.runInThisContext(code)(); 

and it works. Would the modification cause potential problem?

There is also a note in the doc, point out that share reference of require could introduce risk. To my understanding, the modified code is now safe, correct?

via minexu