Generic XHR (post, get, put, delete JSON requests)

loader.js

/*****************************************************************************\
  options
    uri: {}      - key value paris of data to send in url/get/uri
    data: {}||'' - Object or string to be sent as JSON data in the body
                   for methods that support body data
    dataType: '' - Data type that is being sent, by default application/json
                   is used.  If you use anything but json|jsonp|application/json
                   make sure your data is already encoded properly as a string

  Loader.get(uri, options, callback)

  Loader.post(uri, options, callback)

  Loader.put(uri, options, callback)

  Loader.patch(uri, options, callback)

  Loader.delete(uri, options, callback)

\*****************************************************************************/
({define:typeof define!=="undefined"?define:function(deps, factory){
  module.exports = typeof(module)!=='undefined'?
                     module.exports = factory():
                     window.Loader = factory();
  /*
  if(typeof(module)!=='undefined'){
    module.exports = factory();
  }else{
    window.Loader = factory();
  }
  */
}}).
define([], function(){
  var Loader = {};
  var callhashlist = [], callbacks = [];

  Loader.dataTypes={
    'json': 'application/json',
    'jsonp': 'application/json'
  };

  var addCallback = function(hash, callback){
    var idx = callhashlist.indexOf(hash), found = idx>-1;
    if(!found){
      idx = callhashlist.length;
      callhashlist[idx] = hash;
      callbacks[idx]=[];
    }
    callbacks[idx].push(callback);
    return found;
  };

  var callCallbacks = function(hash, err, results){
    var idx = callhashlist.indexOf(hash), cbs, i, l;
    if(idx>-1){
      cbs = (callbacks.splice(idx, 1)||[])[0]||[];
      callhashlist.splice(idx, 1);
      l = cbs.length;
      for(i=0; i<l; i++){
        cbs[i](err, results);
      }
    };
  };

  var RemoteRequest = function(){
    if (window.ActiveXObject){
      var activexmodes=["Msxml2.XMLHTTP", "Microsoft.XMLHTTP"];
      for (var i=0; i<activexmodes.length; i++){
        try{
          return new ActiveXObject(activexmodes[i])
        }catch(e){
          //suppress error
        }
      }
    }
    if (window.XMLHttpRequest){
      return new XMLHttpRequest()
    }
    return false
  };

  var encodeParams = function(args){
    var key, s=[], i, l;
    var addParam = function(key, value){
      value = value instanceof Function?value():(value===null?'':value);
      s[s.length]=encodeURIComponent(key)+'='+encodeURIComponent(value);
    };
    if(args instanceof Array){
      l = args.length;
      for(i=0; i<l; i++){
        addParam(args[i].name, args[i].value);
      }
    }else if(args){
      for(key in args){
        addParam(key, args[key]);
      }
    }
    return s.join('&').replace(/%20/g, '+');
  };

  var defineMethod = function(HTTPMethod){
    Loader[HTTPMethod] = function(resourceURI, options, callback){
      var getParams='', requestData, callHash, url = resourceURI;
      var requestObject, response, items, body, dataType;
      if(typeof(options)==='function'){
        callback = options;
        options = {};
      }
      callback=callback||function(){};
      options=options||{};
      if(typeof(options.uri)==='string'){
        try{
          options.uri=JSON.parse(options.uri);
        }catch(e){}
      }
      options.uri=options.uri||{};
      callHash = resourceURI+JSON.stringify(options.uri)+JSON.stringify(options.data);
      if(!addCallback(callHash, callback)){
        options.uri.ts = new Date();
        url += ((url||'').indexOf('?')===-1?'?':'&') + encodeParams(options.uri);
        requestObject = new RemoteRequest();

        requestObject.onreadystatechange=function(){
          if(requestObject.readyState===4){
            if (requestObject.status===200 || window.location.href.indexOf("http")===-1){
              try{
                response = JSON.parse(requestObject.responseText);
              }catch(e){
                response = requestObject.responseText;
              }
              if(response.error||response.errors){
                callCallbacks(callHash, response);
              }else{
                items=response[response.root];
                try{
                  response = (items instanceof Array)?{
                    items: items,
                    offset: response.offset,
                    limit: response.limit,
                    count: response.count||items.length,
                    length: response.length||items.length
                  }:items||response;
                }catch(e){
                }
                callCallbacks(callHash, null, response);
              }
            }else{
              var err = new Error(requestObject.statusText+': '+(requestObject.responseText||requestObject.response));
              err.type = requestObject.statusText;
              err.code = requestObject.status;
              err.requestObject = requestObject;
              callCallbacks(callHash, err);
            }
          }
        };

        requestObject.open(HTTPMethod.toUpperCase(), url, true);
        if(options.data){
          dataType=Loader.dataTypes[options.dataType]||options.dataType||"application/json";
          if(options.data instanceof FormData){
            body = options.data;
          }else{
            requestObject.setRequestHeader("Content-type", dataType);
            try{
              body = JSON.stringify(options.data);
            }catch(e){
              body = options.body;
            };
          }
          if(options.headers){
            (function(){
              var key;
              for(key in options.headers){
                try{
                  requestObject.setRequestHeader(key, options.headers[key]);
                }catch(e){}
              }
            })();
          }
          requestObject.send(body);
        }else{
          requestObject.send(null);
        }
      }
    };
  };

  Loader.form = function(method, form, callback){
    var formData = new FormData(form);

    var callHash = form.action + (new Date()).getTime();
    if(!addCallback(callHash, callback)){
      var requestObject = new RemoteRequest();
      requestObject.onreadystatechange=function(){
        if(requestObject.readyState===4){
          if (requestObject.status===200 || window.location.href.indexOf("http")===-1){
            try{
              response = JSON.parse(requestObject.responseText);
            }catch(e){
              response = requestObject.responseText;
            }
            if(response.error||response.errors){
              callCallbacks(callHash, response);
            }else{
              items=response[response.root];
              try{
                response = (items instanceof Array)?{
                  items: items,
                  offset: response.offset,
                  limit: response.limit,
                  count: response.count,
                  length: items.length
                }:items||response;
              }catch(e){
              }
              callCallbacks(callHash, null, response);
            }
          }else{
            var err = new Error(requestObject.statusText+': '+(requestObject.responseText||requestObject.response));
            err.type = requestObject.statusText;
            err.code = requestObject.status;
            err.requestObject = requestObject;
            callCallbacks(callHash, err);
          }
        }
      };
      requestObject.open(method.toUpperCase(), form.action, true);
      requestObject.send(formData);
    }
    return false;
  };

  Loader.postForm = function(form, callback){
    Loader.form('POST', form, callback);
  };

  Loader.putForm = function(form, callback){
    Loader.form('PUT', form, callback);
  };

  (function(methods, callback){
    var i, l=methods.length;
    for(i=0; i<l; i++){
      callback(methods[i]);
    }
  })(['get', 'post', 'put', 'patch', 'delete'], defineMethod);
  return Loader;
});