javascript中Date对象的应用——简易日历的实现

  简易日历作为javascript中Date对象的常见应用,用途较广泛。本文将详细说明简易日历的实现思路

 

效果演示

 

HTML说明

  使用type=number的两个input分别作为年和月的输入控件,这样在高级浏览器下自带调节按钮

  按照周日到周六的顺序进行星期的排列

<div class="box">
    <header class='control'>
        <input id="conYear" class="con-in" type="number" min="1900" max="2100" step="1"/>
        <input id="conMonth" class="con-in" type="number" min="1" max="12" step="1"/>
    </header>
    <div class="DateBox">
        <header class='week'>
            <div class="week-in">周日</div>
            <div class="week-in">周一</div>
            <div class="week-in">周二</div>
            <div class="week-in">周三</div>
            <div class="week-in">周四</div>
            <div class="week-in">周五</div>
            <div class="week-in">周六</div>
        </header>
        <section class="dayBox" id='dayBox'>
            <div class="day" id="day1">1</div>
            <div class="day">2</div>
            <div class="day">3</div>
            <div class="day">4</div>
            <div class="day">5</div>
            <div class="day">6</div>
            <div class="day">7</div>
            <div class="day">8</div>
            <div class="day">9</div>
            <div class="day">10</div>
            <div class="day">11</div>
            <div class="day">12</div>
            <div class="day">13</div>
            <div class="day">14</div>
            <div class="day">15</div>
            <div class="day">16</div>
            <div class="day">17</div>
            <div class="day">18</div>
            <div class="day">19</div>
            <div class="day">20</div>
            <div class="day">21</div>
            <div class="day">22</div>
            <div class="day">23</div>
            <div class="day">24</div>
            <div class="day">25</div>
            <div class="day">26</div>
            <div class="day">27</div>
            <div class="day">28</div>
            <div class="day">29</div>
            <div class="day" id="day30">30</div>
            <div class="day" id="day31">31</div>
        </section>
    </div>    
</div>

 

CSS说明

  对于简易日历的实现,首先确定日历中class="day"的div的排列方式为浮动。这样可以通过改变第一天div的位置,来实现所有同级div都可以跟随移动的效果

body{
    margin: 0;
}
input{
    border: none;
    padding: 0;
}
.box{
    width: 354px;
    margin: 30px auto 0;    
}
.DateBox{
    height: 300px;
    border: 2px solid black;
}    
.week{
    overflow: hidden;
    border-bottom: 1px solid black;
    line-height: 49px;
}
.week-in{
    height: 49px;
    float: left;
    width: 50px;
    text-align: center;
}
.dayBox{
    overflow: hidden;
}
.day{
    float: left;
    height: 50px;
    width: 50px;
    font:20px/50px '微软雅黑';
    text-align: center;
}
.control{
    overflow: hidden;
}
.con-in{
    height: 50px;
    float: left;
    width: 100px;
    text-align: center;
    font: 20px/50px "微软雅黑";
}

 

JS说明

  简易日历的JS逻辑总共需要5个实现:

  【1】需要获取当月的天数,获取当月第一天、第30天、第31天是周几

  【2】根据当月第一天的星期,改变第一天的margin-left值,移动第一天到对应的位置;由于浮动的关系,其余天也会跟着移动到对应的位置

  【3】根据当月的天数,隐藏多余的天;当然,隐藏之前要先显示在其他月份可能被隐藏的天

  【4】如果当月30日是周日,则会新占一行。这时通过改变30日这天的margin值将其移动到第一行(若31日可能会新占一行,也做相似处理)

  【5】载入页面后,获取当前的年和月,显示当月日历;当改变年或月时,获取改变后的值,更新日历

//准备:获取当前样式
function getCSS(obj,style){
    if(window.getComputedStyle){
        return getComputedStyle(obj)[style];
    }
    return obj.currentStyle[style];
}
//实现一:获取当月的天数,及当月第一天、第30日、第31日是星期几
function get_data(year,month){
    var result = {};
    var d = new Date();
    //如果是2月
    if(month == 2){
        //如果是闰年
        if((year % 4 === 0 && year % 100 !== 0)  || year % 400 === 0){
            result.days = 29;
        //如果是平年
        }else{
            result.days = 28;
        }
    //如果是第4、6、9、11月
    }else if(month == 4 || month == 6 ||month == 9 ||month == 11){
        result.days = 30;
    }else{
        result.days = 31;
        //当月第31天是星期几
        result.day31week = d.getDay(d.setFullYear(year,month-1,31));
    }
    //当月第一天是星期几
    result.day1week = d.getDay(d.setFullYear(year,month-1,1));
    if(month != 2){
        //当月第30天是星期几
        result.day30week = d.getDay(d.setFullYear(year,month-1,30));        
    }
    return result;
}
//实现二:根据当月第一天的星期x,设置第一天的margin-left=宽度*x,使其对应到正确的星期位置上
function move_day1(year,month){
    var week1 = get_data(year,month).day1week;
    day1.style.marginLeft = week1%7*parseInt(getCSS(day1,'width'))+ 'px';
}
//实现三:根据当月的天数,来隐藏多余的天数。当然首先要先显示在其他月份被隐藏的天数
function hide_days(year,month){
    //恢复其他月份可能隐藏的天数
    for(var i = 28; i<31; i++){
        dayBox.children[i].style.display = 'block';
    }    
    //隐藏当月多余的天数
    var days = get_data(year,month).days;
    for(var i = days;i<31;i++){
        dayBox.children[i].style.display = 'none';
    }
};
//实现四:如果当月30日或31日是星期日,则会新占一行,通过设置margin-top把新占一行的天移动到第一行
function move_day30(year,month){
    //如果当月30日是星期日
    if(get_data(year,month).day30week === 0){
        day30.style.marginTop = parseInt(getCSS(day30,'height')) *(-5) + 'px';
        day31.style.marginTop = parseInt(getCSS(day31,'height')) *(-5) + 'px';
        day31.style.marginLeft= getCSS(day31,'width');
        return;
    }else{
        day30.style.marginTop = day31.style.marginTop = day31.style.marginLeft ='0';
    }
    //如果当月31日是星期日
    if(get_data(year,month).day31week === 0){
        day31.style.marginTop = parseInt(getCSS(day31,'height')) *(-5) + 'px';
    }else{
        day31.style.marginTop = '0';
    }
}
//实现五:当载入页面时,获取当前年和月,显示当月日历;当改变年或月时,获取改变后的年和月,更新当月日历
var year= conYear.value=new Date().getFullYear();
var month= conMonth.value = new Date().getMonth() + 1;
move_day1(year,month);
hide_days(year,month);
move_day30(year,month);

conYear.onchange = conMonth.onchange = function(){
    var year = conYear.value;
    var month = conMonth.value;
    if(year<1900 || year >2100 ){
        year = conYear.value=new Date().getFullYear();
    }
    if(month<1 || month > 12){
        month = conMonth.value=new Date().getMonth() + 1;
    }
    move_day1(year,month);
    hide_days(year,month);
    move_day30(year,month);
}

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