前端---实现一个简单的日历

╰半橙微兮° 2023-02-19 09:27 311阅读 0赞

**纯JS代码实现**

<!DOCTYPE html>
    <html lang="en">
    
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <meta http-equiv="X-UA-Compatible" content="ie=edge">
      <title>Calendar</title>
      <style>
        .calendar-container {
          padding: 30px;
          width: 576px;
        }
    
        .date-container {
          text-align: center;
          height: 50px;
          line-height: 50px;
        }
    
        /*上一月下一月按钮*/
        #preMonth,#nextMonth {
          position: relative;
        }
        #preMonth:after {
          content: '<';
          position: absolute;
          left: -28px;
          top: -1px;
          width: 24px;
          text-align: center;
          line-height: 24px;
          border-radius: 21px;
          background-color:brown;
          color: white;
        }
        #nextMonth:after {
          content: '>';
          position: absolute;
          left: 4px;
          top: -1px;
          width: 24px;
          text-align: center;
          line-height: 24px;
          border-radius: 21px;
          background-color:brown;
          color: white;
        }
        #nowYear,#nowMonth,#nowDate{
          padding: 0 5px;
        }
    
    
        .week-item {
          display: inline-block;
          width: 80px;
          height: 60px;
          line-height: 60px;
          border: 1px solid #EEEEEE;
          text-align: center;
        }
    
        .date-item {
          display: inline-block;
          width: 80px;
          line-height: 80px;
          border: 1px solid #EEEEEE;
          text-align: center;
        }
      </style>
    </head>
    
    <body>
      <div class="calendar-container">
        <div class="date-container">
          <span id="preMonth" class="year-prev"></span>
          <span id="nowYear" class="year-now"></span>
          <span id="nowMonth"></span>
          <span id="nowDate"></span>
          <span id="nextMonth" class="year-next"></span>
        </div>
        <div id="weekLine" class="week-line"></div>
        <div id="dateWrap" class="date-wrap"></div>
      </div>
    </body>
    
    </html>
    <script>
      // 1.为了获得每个月的日期有多少，我们需要判断 平年闰年[四年一闰，百年不闰，四百年再闰]
      const isLeapYear = (year) => {
        return (year % 400 === 0) || (year % 100 !== 0 && year % 4 === 0);
      };
      // 2.获得每个月的日期有多少，注意 month - [0-11]
      const getMonthCount = (year, month) => {
        let arr = [
          31, null, 31, 30, 
          31, 30, 31, 31,
          30, 31, 30, 31
        ];
        let count = arr[month] || (isLeapYear(year) ? 29 : 28);
        return Array.from(new Array(count), (item, value) => value + 1);
      };
      // 3.获得某年某月的 1号 是星期几，这里要注意的是 JS 的 API-getDay() 是从 [日-六](0-6)，返回 number
      const getWeekday = (year, month) => {
        let date = new Date(year, month, 1);
        return date.getDay();
      };
      // 4.获得上个月的天数
      const getPreMonthCount = (year, month) => {
        if (month === 0) {
          return getMonthCount(year - 1, 11);
        } else {
          return getMonthCount(year, month - 1);
        }
      };
      // 5.获得下个月的天数
      const getNextMonthCount = (year, month) => {
        if (month === 11) {
          return getMonthCount(year + 1, 0);
        } else {
          return getMonthCount(year, month + 1);
        }
      };
      // 工具方法 - end
      let weekStr = '日一二三四五六';
      weekArr = weekStr.split('').map(item => '星期' + item);
      // 插入星期 dom
      let weekDomStr = '';
      let oFragWeek = document.createDocumentFragment();
      weekArr.forEach(item => {
        let oSpan = document.createElement('span');
        let oText = document.createTextNode(item);
        oSpan.appendChild(oText);
        oSpan.classList.add('week-item');
        oFragWeek.appendChild(oSpan);
      });
      let weekWrap = document.getElementById('weekLine');
      weekWrap.appendChild(oFragWeek);
    
      // 这里获得第一次的 数据 数组
      const updateCalendar = (year, month, day) => {
        if (typeof year === 'undefined' && typeof month === 'undefined' && typeof day === 'undefined') {
          let nowDate = new Date();
          year = nowDate.getFullYear();
          month = nowDate.getMonth();
          day = nowDate.getDate();
        }
        // 更新一下顶部的年月显示
        document.getElementById('nowYear').innerHTML = year;
        document.getElementById('nowMonth').innerHTML = month + 1;
        document.getElementById('nowDate').innerHTML = day;
        // 生成日历数据，上个月剩下的的 x 天 + 当月的 28（平年的2月）或者29（闰年的2月）或者30或者31天 + 下个月的 y 天 = 42
        let res = [];
        let currentMonth = getMonthCount(year, month);
        let preMonth = getPreMonthCount(year, month);
        let nextMonth = getNextMonthCount(year, month);
        let whereMonday = getWeekday(year, month);
        if (whereMonday === 0) {
          whereMonday = 7
        }
        // 这里当 whereMonday 为 0 的时候会截取上月的所有数据
        let preArr = preMonth.slice(-1 * whereMonday)
        let nextArr = nextMonth.slice(0, 42 - currentMonth.length - whereMonday);
        res = [].concat(preArr, currentMonth, nextArr);
        // 更新 dom 的信息的问题
        let hadDom = document.getElementsByClassName('date-item');
        if (hadDom && hadDom.length) {
          let domArr = document.getElementsByClassName('date-item');
          for (let i = 0; i < domArr.length; i++) {
            domArr[i].innerHTML = res.shift();
          }
        } else {
          // 如果之前没有结构的话
          let str = '';
          for (let i = 0; i < 5; i++) {
            str += '<div class="date-line">';
            for (let j = 0; j < 7; j++) {
              str += `<span class='date-item'>${res.shift()}</span>`;
              if (j === 6) {
                str += '</div>';
              }
            }
          }
          document.getElementById('dateWrap').innerHTML = str;
        }
      };
    
      updateCalendar();
      // 添加上一月，下一月事件
      let oPreButton = document.getElementById('preMonth');
      let oNextButton = document.getElementById('nextMonth');
      oPreButton.addEventListener('click', function () {
        let currentYear = +document.getElementById('nowYear').textContent;
        let currentMonth = +document.getElementById('nowMonth').textContent - 1;
        let currentDate = +document.getElementById('nowDate').textContent;
        if (currentMonth === 0) {
          updateCalendar(currentYear - 1, 11, currentDate);
        } else {
          updateCalendar(currentYear, currentMonth - 1, currentDate);
        }
      });
      oNextButton.addEventListener('click', function () {
        let currentYear = +document.getElementById('nowYear').textContent;
        let currentMonth = +document.getElementById('nowMonth').textContent - 1;
        let currentDate = +document.getElementById('nowDate').textContent;
        if (currentMonth === 11) {
          updateCalendar(currentYear + 1, 0, currentDate);
        } else {
          updateCalendar(currentYear, currentMonth + 1, currentDate);
        }
      });
    </script>

**使用了Jquery**

<!DOCTYPE html>
    <html lang="en">
    
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <meta http-equiv="X-UA-Compatible" content="ie=edge">
      <title>Calendar</title>
      <style>
        .calendar-container {
          padding: 30px;
          width: 576px;
        }
    
        .date-container {
          text-align: center;
          height: 50px;
          line-height: 50px;
        }
    
        /*上一月下一月按钮*/
        #preMonth,#nextMonth {
          position: relative;
        }
        #preMonth:after {
          content: '<';
          position: absolute;
          left: -28px;
          top: -1px;
          width: 24px;
          text-align: center;
          line-height: 24px;
          border-radius: 21px;
          background-color:brown;
          color: white;
        }
        #nextMonth:after {
          content: '>';
          position: absolute;
          left: 4px;
          top: -1px;
          width: 24px;
          text-align: center;
          line-height: 24px;
          border-radius: 21px;
          background-color:brown;
          color: white;
        }
        #nowYear,#nowMonth,#nowDate{
          padding: 0 5px;
        }
    
    
        .week-item {
          display: inline-block;
          width: 80px;
          height: 60px;
          line-height: 60px;
          border: 1px solid #EEEEEE;
          text-align: center;
        }
    
        .date-item {
          display: inline-block;
          width: 80px;
          line-height: 80px;
          border: 1px solid #EEEEEE;
          text-align: center;
        }
      </style>
    </head>
    
    <body>
      <div class="calendar-container">
        <div class="date-container">
          <span id="preMonth" class="year-prev"></span>
          <span id="nowYear" class="year-now"></span>
          <span id="nowMonth"></span>
          <span id="nowDate"></span>
          <span id="nextMonth" class="year-next"></span>
        </div>
        <div id="weekLine" class="week-line"></div>
        <div id="dateWrap" class="date-wrap"></div>
      </div>
    </body>
    
    </html>
    
    <script src="https://lib.sinaapp.com/js/jquery/2.0.2/jquery-2.0.2.min.js"></script>
    
    <script>
      /**
        * 1.判断平年闰年[四年一闰，百年不闰，四百年再闰]
        */
      function isLeapYear(year) {
        return (year % 400 === 0) || (year % 100 !== 0 && year % 4 === 0);
      }
    
    
      /**
        * 2.获得每个月有几天，注意 month是[0-11]
        */
      function getMonthCount(year, month) {
        let arr = [
          31, null, 31, 30,
          31, 30, 31, 31,
          30, 31, 30, 31
        ];
        let count = arr[month] || (isLeapYear(year) ? 29 : 28);
        return Array.from(new Array(count), (item, value) => value + 1);
      }
    
    
      /**
        * 3.获得某年某月的 1号 是星期几，这里要注意的是 JS 的 API-getDay() 是从 [日-六](0-6)，返回 number
        */
      function getWeekday(year, month) {
        let date = new Date(year, month, 1);
        return date.getDay();
      }
    
      /**
        * 4.获得上个月的天数
        */
      function getPreMonthCount(year, month) {
        if (month === 0) {
          return getMonthCount(year - 1, 11);
        } else {
          return getMonthCount(year, month - 1);
        }
      }
    
    
    
      /**
       * 5.获得下个月的天数
       */
      function getNextMonthCount(year, month) {
        if (month === 11) {
          return getMonthCount(year + 1, 0);
        } else {
          return getMonthCount(year, month + 1);
        }
      }
    
    
    
    
      // 工具方法 - end
      let weekStr = '日一二三四五六';
      weekArr = weekStr.split('').map(item => '星期' + item);
      // 插入星期 dom
      let weekDomStr = '';
      let oFragWeek = document.createDocumentFragment();
      weekArr.forEach(item => {
        let oSpan = document.createElement('span');
        let oText = document.createTextNode(item);
        oSpan.appendChild(oText);
        oSpan.classList.add('week-item');
        oFragWeek.appendChild(oSpan);
      });
      let weekWrap = document.getElementById('weekLine');
      weekWrap.appendChild(oFragWeek);
    
    
      // 这里获得第一次的 数据 数组
      const updateCalendar = (year, month, day) => {
        if (typeof year === 'undefined' && typeof month === 'undefined' && typeof day === 'undefined') {
          let nowDate = new Date();
          year = nowDate.getFullYear();
          month = nowDate.getMonth();
          day = nowDate.getDate();
        }
        // 更新一下顶部的年月显示
        document.getElementById('nowYear').innerHTML = year;
        document.getElementById('nowMonth').innerHTML = month + 1;
        document.getElementById('nowDate').innerHTML = day;
        // 生成日历数据，上个月剩下的的 x 天 + 当月的 28（平年的2月）或者29（闰年的2月）或者30或者31天 + 下个月的 y 天 = 42
        let res = [];
        let currentMonth = getMonthCount(year, month);
        let preMonth = getPreMonthCount(year, month);
        let nextMonth = getNextMonthCount(year, month);
        let whereMonday = getWeekday(year, month);
        if (whereMonday === 0) {
          whereMonday = 7
        }
        // 这里当 whereMonday 为 0 的时候会截取上月的所有数据
        let preArr = preMonth.slice(-1 * whereMonday)
        let nextArr = nextMonth.slice(0, 42 - currentMonth.length - whereMonday);
        res = [].concat(preArr, currentMonth, nextArr);
        // 更新 dom 的信息的问题
        let hadDom = document.getElementsByClassName('date-item');
        if (hadDom && hadDom.length) {
          let domArr = document.getElementsByClassName('date-item');
          for (let i = 0; i < domArr.length; i++) {
            domArr[i].innerHTML = res.shift();
          }
        } else {
          // 如果之前没有结构的话
          let str = '';
          for (let i = 0; i < 5; i++) {
            str += '<div class="date-line">';
            for (let j = 0; j < 7; j++) {
              str += `<span class='date-item'>${res.shift()}</span>`;
              if (j === 6) {
                str += '</div>';
              }
            }
          }
          document.getElementById('dateWrap').innerHTML = str;
        }
      };
    
      updateCalendar();
    
    
      // 点击上一月
      $('#preMonth').click(function () {
        let currentYear = $('#nowYear').html();         //年
        let currentMonth = $('#nowMonth').html() - 1;   //月
        let currentDate = document.getElementById('nowDate').textContent;
        if (currentMonth === 0) {
          updateCalendar(currentYear - 1, 11, currentDate);
        } else {
          updateCalendar(currentYear, currentMonth - 1, currentDate);
        }
      });
    
      // 点击下一月
      $('#nextMonth').click(function () {
        let currentYear = document.getElementById('nowYear').textContent;
        let currentMonth = document.getElementById('nowMonth').textContent - 1;
        let currentDate = document.getElementById('nowDate').textContent;
        if (currentMonth === 11) {
          updateCalendar(currentYear + 1, 0, currentDate);
        } else {
          updateCalendar(currentYear, currentMonth + 1, currentDate);
        }
      });
    </script>

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