Get an array of the parameters defined for a given function

definedParameters.js

function definedParameters(func) {
  return func.toString().split("\n")[0].match(/\({1}.*\){1}/)[0].replace("(","").replace(")","").split(" ").join("").split(",");
}
// definedParameters(function (a,b,c){return a*b*c;}) returns ["a","b","c"];