如果希望将代码用于Dashboard小部件，并且不希望在创建的每个小部件中都包含JavaScript库，那么可以使用Safari本机支持的对象XMLHttpRequest。

据Andrew Hedges报道，默认情况下，小部件不能访问网络;你需要改变信息中的设置。与小部件关联的Plist。

在纯javascript和返回一个承诺:

  httpRequest = (url, method = 'GET') => {
    return new Promise((resolve, reject) => {
      const xhr = new XMLHttpRequest();
      xhr.open(method, url);
      xhr.onload = () => {
        if (xhr.status === 200) { resolve(xhr.responseText); }
        else { reject(new Error(xhr.responseText)); }
      };
      xhr.send();
    });
  }

// Create a request variable and assign a new XMLHttpRequest object to it.
var request = new XMLHttpRequest()

// Open a new connection, using the GET request on the URL endpoint
request.open('GET', 'restUrl', true)

request.onload = function () {
  // Begin accessing JSON data here
}

// Send request
request.send()

对于那些使用AngularJs的人来说，它是$http.get:

$http.get('/someUrl').
  success(function(data, status, headers, config) {
    // this callback will be called asynchronously
    // when the response is available
  }).
  error(function(data, status, headers, config) {
    // called asynchronously if an error occurs
    // or server returns response with an error status.
  });

浏览器(和Dashcode)提供了一个XMLHttpRequest对象，可用于从JavaScript发出HTTP请求:

function httpGet(theUrl)
{
    var xmlHttp = new XMLHttpRequest();
    xmlHttp.open( "GET", theUrl, false ); // false for synchronous request
    xmlHttp.send( null );
    return xmlHttp.responseText;
}

然而，不鼓励同步请求，并将生成如下警告:

注意:从Gecko 30.0 (Firefox 30.0 / Thunderbird 30.0 / SeaMonkey 2.27)开始，由于对用户体验的负面影响，主线程上的同步请求已被弃用。

您应该在事件处理程序中发出异步请求并处理响应。

function httpGetAsync(theUrl, callback)
{
    var xmlHttp = new XMLHttpRequest();
    xmlHttp.onreadystatechange = function() { 
        if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
            callback(xmlHttp.responseText);
    }
    xmlHttp.open("GET", theUrl, true); // true for asynchronous 
    xmlHttp.send(null);
}

你也可以用纯JS来做:

// Create the XHR object.
function createCORSRequest(method, url) {
  var xhr = new XMLHttpRequest();
if ("withCredentials" in xhr) {
// XHR for Chrome/Firefox/Opera/Safari.
xhr.open(method, url, true);
} else if (typeof XDomainRequest != "undefined") {
// XDomainRequest for IE.
xhr = new XDomainRequest();
xhr.open(method, url);
} else {
// CORS not supported.
xhr = null;
}
return xhr;
}

// Make the actual CORS request.
function makeCorsRequest() {
 // This is a sample server that supports CORS.
 var url = 'http://html5rocks-cors.s3-website-us-east-1.amazonaws.com/index.html';

var xhr = createCORSRequest('GET', url);
if (!xhr) {
alert('CORS not supported');
return;
}

// Response handlers.
xhr.onload = function() {
var text = xhr.responseText;
alert('Response from CORS request to ' + url + ': ' + text);
};

xhr.onerror = function() {
alert('Woops, there was an error making the request.');
};

xhr.send();
}

详见:html5rocks教程