js日历

/**
 * @author qiaoYang
 * @time 2012.8.10
 */

var day = new Date();
//申明一个数组存储每个月的天数
var monthOfDays = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
//存储星期的数组
var weeksArray = new Array("Sun","Mon","Tue","Wed","Thu","Fri","Sat");
//存储月份的数组
var monthss = new Array("January","February","March","April","May","June","July","August","September","October","November","December");

/**
 * @func
 */
function loadFunction(func){
    var oldOnLoad = window.onload;
    if(typeof window.onload != "function"){
        window.onload = func;
    }else{
        window.onload = function(){
            oldOnLoad();
            func();
        };
    }
}

/**
 * 判断年份是否为闰年
 * @param year 
 * @returns {Number}
 */

function isLeap(year){
    if((year%4 ==0) || (year%100 == 0 && year%400 ==0))
        return 1;
    else
        return 0;
}

/**
 * 计算每个月的第一天是星期几的函数
 * @param year
 * @param month
 * @returns
 */
function calFirstOfMonth(year, month){
    var day = new Date(year,month,1);
    return day.getDay();
}

/**
 * 计算需要的表格的行数
 * @param year 表示的年份
 * @param months 表示的月份
 * @param blanks 表示1号与星期几对齐
 * @returns
 */
function calRows(year, months, blanks){
    if(isLeap(year) && months == 1){
        monthOfDays[1] = 29;
    }
    return Math.ceil((monthOfDays[months]+blanks)/7);
}


/**
 * 设置选择以后的年份
 * @param year
 */
function setYear(year){
    alert("hello");
    if(year)
        day.setFullYear(year);
}

/**
 * 设置选择以后的月份
 * @param month
 */
function setMon(month){
    if(month)
        day.setMonth(month);
}

/**
 * 程序初始化
 */
function init(){
    var today = day;
    document.write("<form name='cal'><table bgcolor='f8f8f8' border='1'><tr>");
    document.write("<td colspan='7' bgcolor='#f8f8f8' >");
    document.write("<select name='years' onchange='setYear(2011)' style=' 190px'>");
    for(var i = 1950; i<2500; i++)
        if(i != today.getFullYear())
            document.write("<option value=" + i +">"+i);
        else
            document.write("<option value=" + i +" selected='true'>"+i);
    document.write("</select>");
    document.write("<select name='months' style=' 200px'>");
    for(var i = 1; i<13; i++)
        if(i != today.getMonth()+1)
            document.write("<option value=" + i +">"+monthss[i-1]);
        else
            document.write("<option value=" + i +" selected='true'>"+monthss[i-1]);
    document.write("</select>");
    document.write("</td></tr><tr>");
    for(var i = 0; i < weeksArray.length; i++){
        document.write("<td width='40' align='center'>" + weeksArray[i] + "</td>");
    }
    document.write("</tr>");
    //计算空格数
    var blankNumber = calFirstOfMonth(today.getFullYear(), today.getMonth());
    //计算所需行数
    var rowsNumber = calRows(today.getFullYear(), today.getMonth(), blankNumber);
    for(var i = 0; i<rowsNumber; i++){
        document.write("<tr>");
        for(var j = 0; j < 7; j++){
            if((i == 0 && j < blankNumber) || ((i*7+j-blankNumber+1) > monthOfDays[today.getMonth()] )){
                document.write("<td width='40'>&nbsp;</td>");
            }else{
                document.write("<td width='40' align='center'>" +(i*7+j-blankNumber+1) + "</td>" );
            }
        }
    }
    document.write("</tr></table></form>");
}

loadFunction(init);