JavaScript实现生日选择效果

<script type="text/javascript">

function pageInit(){

makeYear();

makeMonth();

makeDay();

document.getElementById("year").onchange = makeDay;

document.getElementById("month").onchange = makeDay;

}

function makeYear(){

//填充年份

var year = document.getElementById("year");

//如果year是""(空串)删除

if(year.value=="")

year.options.length=0;

//添加option

//今年是何年

var now = new Date().getFullYear();

for(var x=1990; x<=now; x++){

/*

var option = document.createElement("option");

option.value = x;

option.innerHTML = x;//option.innerText = x;

year.appendChild(option);

*/

if(year.value==x)

continue;

year.options.add(new Option(x,x));

}

}

function makeMonth(){

//填充月份

var month = document.getElementById("month");

//如果month是""(空串)删除

if(month.value=="")

month.options.length=0;

for(var x=1; x<=12; x++){

if(month.value==x)

continue;

month.options.add(new Option(x,x));

}

}

function makeDay(){

//填充日期

var day = document.getElementById("day");

//如果day是""(空串)删除

if(day.value=="")

day.options.length=0;

else

day.options.length=1;

var daysNum = getDaysNum();

for(var x=1; x<=daysNum; x++){

if(day.value==x)

continue;

day.options.add(new Option(x,x));

}

}

function getDaysNum(year,month){

//获取天数

var year = document.getElementById("year").value;

var month = document.getElementById("month").value;

var temp = new Date(year,month,0);

var getDays = new Date(temp.getTime()-1000*60*60*24);

return temp.getDate();

}

window.onload = pageInit;

</script>