改造请求参数-Ajax之二
接上篇。引入了一个私有函数_serialize，它会把js对象串行化成HTTP所需参数模式，接受如下两种结构
{name:'jack',age:20} --> name=jack&age=20
{fruit:['apple','banana','orange']} --> fruit=apple&fruit=banana&fruit=orange
请求后台的一个servlet，发送参数name=jack,age=20，默认使用异步，GET方式。现在data可以如下了
Ajax.request('servlet/ServletJSON',{
data : {name:'jack',age:20},
success : function(xhr){
//to do with xhr
},
failure : function(xhr){
//to do with xhr
}
}
);
完整代码
Ajax =
function(){
function request(url,opt){
function fn(){}
var async = opt.async !== false,
method = opt.method || 'GET',
encode = opt.encode || 'UTF-8',
data = opt.data || null,
success = opt.success || fn,
failure = opt.failure || fn;
method = method.toUpperCase();
if(data && typeof data == 'object'){//对象转换成字符串键值对
data = _serialize(data);
}
if(method == 'GET' && data){
url += (url.indexOf('?') == -1 ? '?' : '&') + data;
data = null;
}
var xhr = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
xhr.onreadystatechange = function(){
_onStateChange(xhr,success,failure);
};
xhr.open(method,url,async);
if(method == 'POST'){
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded;charset=' + encode);
}
xhr.send(data);
return xhr;
}
function _serialize(obj){
var a = [];
for(var k in obj){
var val = obj[k];
if(val.constructor == Array){
for(var i=0,len=val.length;i<len;i++){
a.push(k + '=' + encodeURIComponent(val[i]));
}
}else{
a.push(k + '=' + encodeURIComponent(val));
}
}
return a.join('&');
}
function _onStateChange(xhr,success,failure){
if(xhr.readyState == 4){
var s = xhr.status;
if(s>= 200 && s < 300){
success(xhr);
}else{
failure(xhr);
}
}else{}
}
return {request:request};
}();
这里仅仅是使data可以是对象类型，貌似没啥大用。但如果与表单(form)结合的话还是很有用的。当我们使用form但又想用Ajax方式提交，那么把form中元素序列化成HTTP请求的参数类型是一个费劲的活。这里写个工具函数formToHash，将form元素按键值形式转换成对象返回
function formToHash(form){
var hash = {}, el;
for(var i = 0,len = form.elements.length;i < len;i++){
el = form.elements[i];
if(el.name == "" || el.disabled) continue;
switch(el.tagName.toLowerCase()){
case "fieldset":
break;
case "input":
switch(el.type.toLowerCase()){
case "radio":
if(el.checked)
hash[el.name] = el.value;
break;
case "checkbox":
if(el.checked){
if(!hash[el.name]){
hash[el.name] = [el.value];
}else{
hash[el.name].push(el.value);
}
}
break;
case "button":
break;
case "image":
break;
default:
hash[el.name] = el.value;
break;
}
break;
case "select":
if(el.multiple){
for(var j = 0, lens = el.options.length;j < lens; j++){
if(el.options[j].selected){
if(!hash[el.name]){
hash[el.name] = [el.options[j].value];
}else{
hash[el.name].push(el.options[j].value);
}
}
}
}else{
hash[el.name] = el.value;
}
break;
default:
hash[el.name] = el.value;
break;
}
}
form = el = null;
return hash;
}
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