http.js : XMLHttpRequest を利用してHTTPリクエストする

http.js

var XMLHttpRequest = (typeof XMLHttpRequest === 'function' || typeof XMLHttpRequest === 'object') ? XMLHttpRequest : (function () {
  var i, l;

  for (i = 0, l = arguments.length; i < l; i++) {
    try {
      arguments[i]();
      return arguments[i];
    }
    catch (error) {}
  }

  throw new Error('XMLHttpRequest is not defined');
})(function () { return new ActiveXObject('Msxml2.XMLHTTP.6.0'); }, function () { return new ActiveXObject('Msxml2.XMLHTTP.3.0'); });


// HTTP constructor

function HTTP () {
  if (!(this instanceof HTTP)) {
    throw new Error(this + ' is not a object created by constructor');
  }
  return this;
}


// HTTP.prototype

(function () {

  // createReadystatechangeHandler(callbackfn [, thisObject, xhr])

  function createReadystatechangeHandler (callbackfn, thisObject, xhr) {
    var listener;

    if (typeof callbackfn !== 'function') {
      throw new TypeError(callbackfn + ' is not a function');
    }

    listener = function (event) {
      var responseText, responseXML;

      if (event && event.target) {
        xhr = event.target;
      }
      if (typeof xhr !== 'object') {
        throw new TypeError(xhr + ' is not a object');
      }

      if (xhr.readyState === 4) {
        if (xhr.status === 200) {

          responseText = xhr.responseText;
          responseXML = xhr.responseXML;

          if (responseText || responseXML) {

            if (thisObject) {
              callbackfn.call(thisObject, responseText, responseXML);
            } else {
              callbackfn(responseText, responseXML);
            }

          }
        }

//        xhr.abort();  // Google Chrome 6 returns an error : XMLHttpRequest Exception 101

        if (xhr.removeEventListener) {
          xhr.removeEventListener('readystatechange', listener, false);
        } else {
          xhr.onreadystatechange = new Function;
        }
        callbackfn = thisObject = xhr = listener = null;
      }
    };

    return listener;
  }


  // HTTP.prototype.request(method, url [, callbackfn, options])

  this.request = function (method, url, callbackfn, options) {
    var async, data, thisObject, xhr, isDocument;

    // default value
    async = false;
    data = null;

    if (options !== null && typeof options === 'object') {
      if ('async' in options) {
        async = options.async;
      }
      if ('data' in options) {
        data = options.data;
      }

      thisObject = options.thisObject;
    }

    if (typeof url !== 'string') {
      throw new TypeError(method + ' is not a string');
    }

    // RFC 2616 (HTTP/1.1)
    if (method !== 'GET' && method !== 'POST' && method !== 'HEAD' && method !== 'PUT' && method !== 'OPTIONS' && method !== 'DELTE' && method !== 'TRACE' && method !== 'CONNECT') {
      throw new TypeError(method + ' is not a method (RFC 2616)');
    }

    if (method === 'GET' || method === 'HEAD') { // XMLHttpRequest (3.6.3. The send() method)
      data = null;
    }

    if (data !== null && typeof data === 'object' && data.nodeType === 9) {
      isDocument = true;
    }

    if (data !== null && !isDocument && typeof data !== 'string') { // XMLHttpRequest (3.6.3. The send() method)
      throw new TypeError(data + ' is not a null or document or string');
    }

    async = Boolean(async);


    xhr = new XMLHttpRequest;
    xhr.open(method, url, async);

    if (typeof callbackfn === 'function') {
      if (xhr.addEventListener) {
        xhr.addEventListener('readystatechange', createReadystatechangeHandler(callbackfn, thisObject), false); // XMLHttpRequest (3.4. Event Handler Attributes)
      } else {
        xhr.onreadystatechange = createReadystatechangeHandler(callbackfn, thisObject, xhr); // [IE8] Handler's thisObject is not [object XMLHttpRequest]
      }
    }

    xhr.setRequestHeader('Pragma', 'no-cache');
    xhr.setRequestHeader('Cache-Control', 'no-cache');
    xhr.setRequestHeader('If-Modified-Since', 'Thu, 01 Jun 1970 00:00:00 GMT');

    // XMLHttpRequest (3.6.3. The send() method)
    if (isDocument) {
      xhr.setRequestHeader('Content-Type', 'application/xml');
    } else if (method === 'POST') {
      xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    } else if (typeof data === 'string') {
      xhr.setRequestHeader('Content-Type', 'text/plain; charset=UTF-8');
    }

    xhr.send(data);
  };


  // HTTP.prototype.get(url [, callbackfn, options])

  this.get = function (url, callbackfn, options) {
    this.request('GET', url, callbackfn, options);
  };

}).call(HTTP.prototype);