script-handler

Run a custom JS function inside vm, providing a flexible way to validate complex input. Simple to use and does only one thing, so no bells and whistles, which might be just what you need.

Install

npm i script-handler

Usage

script-handler allows you to define a function within a vm, which can then be used to validate complex input.

A script can come from any source (security is outside the scope of this module) and is compiled only once, saving precious time.

The script defines a global variable process, which should be a function. process can then be called with arbitrary data by using compiled.process() (see example below).

A simple annotated example should suffice:

const ScriptHandler = require('script-handler')

// Our script defines a `process` variable which is the function
// that will be called later.
const script = `process = function (row) {
  return row.type === 'credit' && row.code === 'ba'
}`

// We only have to compile the script once, saving clock cycles
const compiled = new ScriptHandler(script)

// In order for the script to set the `process` variable, we have to run it
// When the script has finished running, the global variable `process`
// should be a function (typeof process === 'function')
compiled.run().then(() => {
  // Now our process handler is set
  console.log('Script successfully ran')

  // Some data to validate.
  // vm.process() only supports one argument at the moment
  const row = {
    type: 'credit',
    code: 'ba'
  }

  // Execute the process handler with the `row` data
  // In this case, `valid` will be true
  const valid = vm.process(row)
  console.log(`Row valid: ${valid}`)
}).catch(err => {
  console.log(err)
})

To Do

• Allow any arbitrary amount of arguments to be passed to process
• Try to find a way to make calling vm.process() asynchronous
• Update example to show how to make use of options and sandbox

Changelog

• v0.0.1 (31-03-2017)
  • First published

License

Copyright 2017 Michiel van der Velde.

This software is licensed under the MIT License.