Form序列化

function serialize(form){
 var parts = [],
 field = null,
 i,
 len,
 j,
 optLen,
 option,
 optValue;

 for (i=0, len=form.elements.length; i < len; i++){
 field = form.elements[i];

 switch(field.type){
 case "select-one":
 case "select-multiple":
 if (field.name.length){
 for (j=0, optLen = field.options.length; j < optLen; j++){ 
 option = field.options[j];
 if (option.selected){
 optValue = "";
 if (option.hasAttribute){
 optValue = (option.hasAttribute("value") ?
 option.value : option.text);
 } else {
 optValue = (option.attributes["value"].specified ?
 option.value : option.text);
 }
 parts.push(encodeURIComponent(field.name) + "=" +
 encodeURIComponent(optValue));
 }
 }
 }
 break;

 case undefined: //字段集
 case "file": //文件输入
 case "submit": //提交按钮
 case "reset": //重置按钮
 case "button": //自定义按钮
 break;

 case "radio": //单选按钮
 case "checkbox": //复选框
 if (!field.checked){
 break;
 }
 /* 执行默认操作 */
 default:
 //不包含没有名字的表单字段
 if (field.name.length){
 parts.push(encodeURIComponent(field.name) + "=" +
 encodeURIComponent(field.value));
 }
 }
 }
 return parts.join("&");
}