parameters.js

// get a function's parameters as [...string]
(function() {  
  if (Function.prototype.parameters)
    return;  
  Object.defineProperty(Function.prototype, "parameters", { get: function() {
    var pattern = /^(?:(?:(?:function\s+[\w_\$][\w\d_\$]*)|function\s*|[\w_\$][\w\d_\$]*)(?:\(|[\w_\$])|\(|)(\s*(([\w_\$][\w\d_\$]*)([,\s]*)?)*)/gim
    var matches = pattern.exec(this.toString())
    return matches[1].split(',').map(s => s.trim()).filter(s => s.length)
  }})
})()