用JS写的一个Ajax库(实例代码)

myajax.get({
<span style="white-space:pre">	</span>data: {}, //参数
	url: "", //请求地址
	//发生错误是调用
	error: function(data) {
	},
	//请求成功调用
	success: function(data){		
<span style="white-space:pre">	</span>//eval(data); 将字符串转换成json
	}
});

myajax.post({
	data: {}, //参数
	url: "", //
	//发生错误是调用
	error: function(data) {
	},
	//请求成功调用
	success: function(data){
	//eval(data); 将字符串转换成json
	}
});

myajax.getJSONP({
//参数
data: {
},
url: "", //请求地址
//请求成功调用
success: function(data) {
},
//发生错误时调用
error: function() {
}
});

var myajax = {

	post: function(params){
		var xmlhttp = this.createXMLHttpRequest();
		if (xmlhttp != null)
		{
			var async = true;
			if (typeof params.async != "undefined")
				async = params.async;
			var data = null;
			if (typeof params.data != "undefined")
				data = params.data;
			var url = "";
			if (typeof params.url != "undefined")
				url = params.url;
			if (url == null || url.length == 0)
				return;
			xmlhttp.open("POST", url, async);
			if (async){
				xmlhttp.onreadystatechange = function(){
				
					if (this.readyState==4){
						if (this.status==200){

							if (typeof params.success != "undefined") {
								params.success(xmlhttp.responseText);
							}
						}
						else {
							if (typeof params.error != "undefined") {
								params.error(xmlhttp.status + xmlhttp.statusText);
							}
							console.error(url + ": " + xmlhttp.status);
						}
					}
				};
			}
			
			xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
			var param = "";
			for (var prop in data) {
				param += prop + "=" + data[prop] + "&";
			}
			param = param.substring(0, param.length - 1);
			xmlhttp.send(param);
			if (!async) {
				
				if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
		
					if (typeof params.success != "undefined") {
						params.success(xmlhttp.responseText);
					}
				else {
					if (typeof params.error != "undefined") {
						params.error(xmlhttp.status + xmlhttp.statusText);
					}
					console.error(url + ": " + xmlhttp.status);
				}
				
			}
		}
	},
	get: function(params){
		var xmlhttp = this.createXMLHttpRequest();
		if (xmlhttp != null)
		{
			var async = true;
			if (params.async != undefined)
				async = params.async;
			var url = "";
			if (params.url != undefined)
				url = params.url;
			if (url == null || url.length == 0)
				return;
			if (params.data != null) {
				var data = params.data;
				var paramPrefix = url.indexOf("?") == -1 ? "?" : "&";
		
				url = url + paramPrefix;
				for (var prop in data) {
					url += prop + "=" + data[prop] + "&";
				}
				url = url.substring(0, url.length - 1);
			}
			xmlhttp.open("GET", url, async);
			if (async){
				xmlhttp.onreadystatechange = function(){
					if (this.readyState==4){
						if (this.status==200){
							if (typeof params.success != "undefined") {
								params.success(xmlhttp.responseText);
							}
						}
						else {
							if (typeof params.error != "undefined") {
								params.error(xmlhttp.status + xmlhttp.statusText);
							}
							console.error(url + ": " + xmlhttp.status);
						}
					}
				};
			}

			xmlhttp.send(null);
			if (!async) {
				if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
					if (typeof params.success != "undefined") {
						params.success(xmlhttp.responseText);
					}
				else {
					if (typeof params.error != "undefined") {
						params.error(xmlhttp.status + xmlhttp.statusText);
					}
					console.error(url + ": " + xmlhttp.status);
				}
						
				
			}
		}
	},
	createXMLHttpRequest: function(){
		if (window.XMLHttpRequest)
		{
			return new XMLHttpRequest();
		}
		else if (window.ActiveXObject)
		{
		//code for IE5 and IE6
			return new ActiveXObject("Microsoft.XMLHTTP");
		}
		return null;
	},
	getJSONP: function(params) {

		var url = null;
		if (typeof params.url != "undefined") {
			url = params.url;
		}
		if (url == null) {
			return;
		}
		
		var ff = "" + new Date().getTime() + (parseInt(Math.random() * 10000000000));
		eval("jsonpCallback_" + ff + "=" + function(data){
	
			if (typeof params.success != "undefined") {
				params.success(data);
			}
		});

		//根据url中是否出现过 "?" 来决定添加时间戳参数时使用 "?" 还是 "&" 
		var paramPrefix = url.indexOf("?") == -1 ? "?" : "&";

		url = url + paramPrefix + "jsonpCallback=" + "jsonpCallback_" + ff;
		var param = "";

		if (typeof params.data != "undefined" && params.data != null) {
		
			var data = params.data;
			for (var prop in data) {
				param += prop + "=" + data[prop] + "&";
			}
			param = param.substring(0, param.length - 1);
		}
		if (param.length > 0)
		url = url + "&" + param; 
		var script = document.createElement("script"); 
		document.body.appendChild(script); 
		script.src = url; 
		script.charset ="UTF-8";
		// for firefox, google etc.
		script.onerror = function() {
			if (typeof params.error != "undefined") {
				params.error();
			}
			
	 	}
		script.onload = function() {

		document.body.removeChild(script); 
		} 
		// for ie 
		script.onreadystatechange = function() { 
		  if (this.readyState == "loaded" || this.readyState == "complete") { 
		    document.body.removeChild(script);
		  } 
		}
	}

};