gistfile1.js

// Instead of creating a new validator for each request, just make one and reuse it.
const validator = new OptionsValidator({
  url: {
    //XXXzpao should probably verify that url is a valid url as well
    is:  ["string"]
  },
  onComplete: {
    is:  ["function"],
    msg: "onComplete is required and must be a function"
  },
  headers: {
    map: function (v) v || {},
    is:  ["object"],
    msg: "headers must be an object"
  },
  content: {
    map: function (v) v || null,
    is:  ["string", "object", "null"],
    msg: "content must be a string or an object"
  },
  contentType: {
    map: function (v) v || "application/x-www-form-urlencoded",
    is:  ["string"]
  }
});

const REUSE_ERROR = "This request object has been used already. You must " +
                    "create a new one to make a new request."

exports.Request = apiUtils.publicConstructor(Request);

function Request(options) {
  const self = this;
  // request will hold the actual XHR object
  let request;
  let response;

  options = validator.validateOptions(options);

// ..............

  // Map these setters/getters to the options
  ["url", "headers", "onComplete", "content", "contentType"].forEach(function (k) {
    this.__defineGetter__(k, function () options[k]);
    this.__defineSetter__(k, function (v) {
      // This will automatically rethrow errors from apiUtils.validateOptions.
      return options[k] = validator.validateSingleOption(k, v);
    });
  }, this);

// ..............

// apiUtils.validateOptions doesn't give the ability to easily validate single
// options, so this is a wrapper that provides that ability.
function OptionsValidator(rules) {
  this.rules = rules;

  this.validateOptions = function (options) {
    return apiUtils.validateOptions(options, this.rules);
  }

  this.validateSingleOption = function (field, value) {
    // We need to create a single rule object from our listed rules. To avoid
    // JavaScript String warnings, check for the field & default to an empty object.
    let singleRule = {};
    if (field in this.rules) {
      singleRule[field] = this.rules[field];
    }
    let singleOption = {};
    singleOption[field] = value;
    // This should throw if it's invalid, which will bubble up & out.
    return apiUtils.validateOptions(singleOption, singleRule)[field];
  }
}