JS年月日下拉列表

// JavaScript Document
var $ = function(id) { return ('string' == typeof id ? document.getElementById(id) : id); };
var Extend = function(destination, source) {
for(var pro in source) {
destination[pro] = source[pro];
}
return destination;
}
var addEvent = function(obj, type, fn) {
if(obj.addEventListener) {
obj.addEventListener(type, fn, false);
return true;
}else if(obj.attachEvent) {
obj['e'+type+fn] = fn;
obj[type+fn] = function(){
obj['e'+type+fn](window.event);
}
obj.attachEvent('on'+type, obj[type+fn]);
return true;
}
return false;
}

function DateSelector(idYear, idMonth, idDay, options) {
var D = new Date();
this.year = $(idYear);
this.month = $(idMonth);
this.day = $(idDay);
this.nowYear = D.getFullYear();
this.nowMonth = D.getMonth() + 1;
this.nowDate = D.getDate();
Extend(this, this.setOptions(options));
};
DateSelector.prototype = {
setOptions: function(options){
// 默认项
this.options = {
floorYear: 100, // 距当前年份前100年
ceilYear: 0, // 距当前年份后0年
onStart: function(){}, // 前置事件
onEnd: function(){} // 结束事件
};
return Extend(this.options, options || {});
},
//创建option
createOption: function(container, start, end, sign){
sign = sign || start;
var _num = parseInt(end-start+1, 10); container.options.length = _num;
for(var i = 0; i < _num; i++) {
container.options[i].text = container.options[i].value = start + i;
}
container.selectedIndex = (sign-start >= _num ? _num-1 : sign-start);
},
// 获取年月对应的日期数
getDate: function(y, m){
return new Date(y, m, 0).getDate();
},
// 获取option-text
getSelText: function(sel) {
return sel.options[sel.selectedIndex].text;
},
// 年月日切换
changeDate: function(bindO){
var _this = this;
addEvent(bindO, 'change', function(){
var y = _this.getSelText(_this.year), m = _this.getSelText(_this.month), d = _this.getSelText(_this.day);
_this.createOption(_this.day, 1, _this.getDate(y, m), d);
_this.onEnd();
});

},
// 绑定相应事件
bindEvents: function(){
var _this = this;
this.changeDate(this.year); this.changeDate(this.month);
addEvent(this.day, 'change', function(){ _this.onEnd(); });
},
// 代码初始化
init: function(){
var _startYear = parseInt(this.nowYear - this.floorYear, 10);
var _endYear = parseInt(this.nowYear + this.ceilYear, 10);
var _endDate = this.getDate(this.nowYear, this.nowMonth, 0);
this.createOption(this.year, _startYear, _endYear, this.nowYear);
this.createOption(this.month, 1, 12, this.nowMonth);
this.createOption(this.day, 1, _endDate, this.nowDate);
this.bindEvents();
this.onStart();
}
};