JS时间下拉列表-------只显示年份

var Calendar = {};
Calendar.$ = function (id){
	return document.getElementById(id);//id选择器
}
/**
 * 初始化方法
 * @param context
 * @param startYear
 * @param floatYear
 */
Calendar.init = function (startYear,floatYear,context){
	try {
		this.constructor = Calendar.init;
		this.context = this.defaultContext;//默认执行上下文
		this.context = context ?  context.nodeType === 1 ? context : this.$(context):context||this.$("calendarSelect");//选择要渲染的空间
		this.context.style.width = "100px";//默认长度
		this.startYear = startYear||new Date().getFullYear();//开始的年份，默认当前年
		this.floatYear = floatYear || 10;//浮动多少年
		this.createOption = createOption(this.startYear,this.floatYear);//创建option
	} catch (e) {
		alert(e);
	}
	return this;
}
/**
 * 创建option
 * @param startYear
 */
function createOption(startYear,floatYear){
	var fragment = document.createDocumentFragment();
	fragment = tempCreateOption(fragment,floatYear,true);
	var currenYearOption = document.createElement("option");
	currenYearOption.selected = 'selected';//设置当前年为选中
	currenYearOption.appendChild(document.createTextNode(startYear))
	fragment.appendChild(currenYearOption);
	fragment = tempCreateOption(fragment,floatYear,false);
	Calendar.context.appendChild(fragment);
	return this;
}


function tempCreateOption(fragment,floatYear,flag){
	for(var i = flag?floatYear:1 ;flag?i>=1:i < floatYear ; flag?i--:i ++){
		var option = document.createElement("option");
		var tmp = flag ? this.startYear+ i : this.startYear-i;
		var text = document.createTextNode(Calendar.startYear + (flag?i:-i));	
		option.appendChild(text);
		fragment.appendChild(option);
	}
	return fragment;
}