JavaScript在线手册

 

  • JavaScript语句:
  •  

    1. if...else语句:

      格式1:


      if (<表达式>)
          <语句1>;
      else
          <语句2>;

      if (<表达式>) <语句1>;
      else <语句2>;

      例:
      <Script>
      var now = new Date();
      var hour = now.getHours();

      if (6 < hour && hour < 18)
          document.write ("辛勤工作才能快乐收割!");
      else
          document.write ("休息一下,充电后再出发。");
      </Script>


      格式2:


      if (<表达式>){
          <语句组1>
      }else{
          <语句组2>
      }



      格式3:


      if (<表达式1>){
          <语句组1>
      }else if (<表达式2>){
          <语句组2>
      }else{
          <语句组3>
      }


      例1:
      <Script>
      var now = new Date();
      var day = now.getDay();
      var dayName;

      if (day == 0) dayName = "星期日";
      else if (day == 1) dayName = "星期一";
      else if (day == 2) dayName = "星期二";
      else if (day == 3) dayName = "星期三";
      else if (day == 4) dayName = "星期四";
      else if (day == 5) dayName = "星期五";
      else dayName = "星期六";

      document.write ("今天是快乐的", dayName);
      </Script>


      例2:
      <Script>
      var now = new Date();
      var day = now.getDay();
      var dayName;

      if (day = 0) dayName = "星期日";
      else if (day = 1) dayName = "星期一";
      else if (day = 2) dayName = "星期二";
      else if (day = 3) dayName = "星期三";
      else if (day = 4) dayName = "星期四";
      else if (day = 5) dayName = "星期五";
      else dayName = "星期六";

      document.write ("今天是快乐的", dayName);
      </Script>

    2.  
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