map positional arguments into options object

argmapify.js

"use strict";

// run `npm install introspect` before
var introspect = require('introspect');

function generateEmail(firstName, lastName, provider) {
  return firstName + "." + lastName + "@" + provider;
}

var argMapify = function(fn, argValues, context) {
  var argDefs = introspect(fn);
  return fn.apply(context, argDefs.map(function(arg) {
    return argValues[arg];
  }));
}

console.log(introspect(generateEmail));
console.log(argMapify(generateEmail, {firstName: "John", lastName: "Smith", "provider": "gmail.com"}));