vm-nodejs

This is a small JavaScript library which attempts to emulate the NodeJS runtime on a V8 VM. It tries to to be as fully compatible with the NodeJS API as possible, while allowing select features to be hooked into. For now, the hooks are limited to the require()-procedure.

🔍 Found an inconsistency with the official NodeJS API that makes some module not work with this VM? Please report it as soon as possible in the issue tracker!

Why

vm-nodejs is different from vm2 in the sense that it does not attempt to provide full isolation, and because of this it is much more lightweight. Above that, it allows hooking into the NodeJS internals in a way that vm2 does not allow.

• Run multiple programs in one process that share the same dependencies in environments with limited memory
• Detect when a script was required and reload dependencies (watch-require)

⚠️ This library is not meant at all to provide complete isolation, merely a way to run multiple NodeJS instances in one process. If you need complete isolation, see the vm2 package.

Installation

$ npm i --save vm-nodejs

API

const NodeVM = require('vm-nodejs')

module.reload()

Reloads the module and all of its dependencies and returns a fresh Module object as if require() had been called for the first time on the module itself and its dependencies.

module.children

The module objects required by this one.

module.exports

The module.exports object is created by the Module system. Sometimes this is not acceptable; many want their module to be an instance of some class. To do this, assign the desired export object to module.exports. Note that assigning the desired object to exports will simply rebind the local exports variable, which is probably not what is desired.

module.filename

The fully resolved filename to the module.

module.id

The identifier for the module. Typically this is the fully resolved filename.

module.parent

The module that first required this one.

module.require(id)

Provides a way to load a module as if require() was called from the original module.

new NodeVM([options])

Create a new NodeJS virtual machine. Currently takes no options.

nodevm.getModule(modulePath)

Acts in much the same way as require()-procedure, except that paths are resolved relative to the current working directory and it returns a reference to the Module object instead of its exports.

nodevm.on('require', cb)

Will trigger cb each time a new require statement is executed within the context of the NodeJS VM. The callback is triggered with a single argument e which contains the following properties:

• module: a module instance that represents the module being required

const NodeVM = require('vm-nodejs')
 
const node = new NodeVM()
 
node.on('require', e => {
  console.log(`Required ${e.module.filename}`)
})
 
node.getModule('index.js')

License

The MIT License

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.