簡單 Ajax 函式庫，不需要 jQuery

demo, readme.js

// 這個簡易的函式庫並沒有 jQuery 特有的完善 Promiss Chain
// 但是，這個函式庫可以讓你在不引入龐大的 jQuery 函式庫情況下，
// 有一種類似於 jQuery 的方便的網絡操作輔助。

// 提交數據
$post('/json/update_user', {
  user: 'Jixun'
}, function (r){
  console.info('Reply From Server:', r);
}));

// 抓取資源
$get('/json/get_user', function (r){
  console.info('Reply From Server:', r);
}));

// 通用方法
$ajax({
  type: 'POST',
  url: '/get_lucky',
  done: function (r) {
    console.info('done!');
  },
  fail: function () {
    console.info('ball!');
  },
  always: function () {
    console.info('get next lucky number ..');
  },
  data: { auth: '1$Jixun' },
  headers: {
    'X-Forwarded-For': '1.2.3.4',
    'X-Real-IP': '4.3.2.1'
  }
});

Simple Ajax.js

// 简易 Ajax 函数
// MIT License, Jixun.Moe
(function (global) {

	var _export = {
		ajax: $ajax,
		post: $post,
		get:  $get 
	};

	function foreach (obj, callback) {
		if (obj) {
			for (var x in obj) {
				if (obj.hasOwnProperty(x)) {
					callback(x, obj[x], obj);
				}
			}
		}
	}

	foreach(_export, function (x, _item) {
		global['$' + x] = _item;
	});

	function isFunction (fn) {
		return 'function' == typeof fn;
	}

	function $ajax (opts) {
		var xhr = new XMLHttpRequest();

		if (!opts.type && opts.data)
			opts.type = 'POST';

		xhr.responseType = opts.dataType || '';

		xhr.open(opts.type || 'GET', opts.url);
		if (opts.type == 'POST' && !(opts.headers && opts.headers.hasOwnProperty('Content-type'))) {
			xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
		}

		foreach(opts.headers, function (headerName, headerValue) {
			xhr.setRequestHeader(headerName, headerValue);
		});

		var postData;

		switch(typeof opts.data) {
			case 'string':
				postData = [opts.data];
				break;

			case 'object':
				if (opts.data instanceof Array) {
					postData = opts.data;
				} else {
					postData = [];
					foreach(opts.data, function (name, value) {
						postData.push(encodeURIComponent(name) + '=' + encodeURIComponent(value));
					});
				}
				break;
		}

		if (!isFunction(opts.always))
			opts.always = emptyFunction;

		xhr.onload = function () {
			var data = tryParseJson(xhr.responseText);
			if (isFunction(opts.done)) {
				opts.done(data, xhr);
			}

			opts.always(xhr.status, xhr);
		};

		if (opts.hasOwnProperty('timeout')) {
			xhr.timeout = parseInt(opts.timeout);
		}

		xhr.onerror = xhr.ontimeout = function () {
			if (isFunction(opts.fail)) {
				opts.fail(xhr.status, xhr);
			}

			opts.always(xhr.status, xhr);
		};

		if (isFunction(opts.preSend))
			opts.preSend(xhr);

		xhr.send(postData ? postData.join('&') : '');
	}

	function $post (url, data, success, fail) {
		$ajax({
			url: url,
			data: data,
			done: success,
			fail: fail
		});
	}

	function $get (url, success, fail) {
		$ajax({
			url: url,
			done: success,
			fail: fail
		});
	}

	function tryParseJson (str) {
		if ('string' == typeof str && str[0] != '{') {
			// If there's an error,
			// roll back to origional string.
			try { return JSON.parse(str); }
			catch (err) {  }
		}
		return str;
	}

	function emptyFunction (){}
})(window);