07:おみくじを作ってみよう

<input id="omikuji" type="button" value="おみくじを引く">
  <script>
      document.getElementById("omikuji").onclick = function(){
      let rnd = Math.floor( Math.random() * 6 );

      switch(rnd){
          case 0:
              omikuji = "大吉";
              break;
          case 1:
              omikuji = "吉";
              break;
          case 2:
              omikuji = "中吉";
              break;
          case 3:
              omikuji = "小吉";
              break;
          case 4:
              omikuji = "末吉";
              break;
          case 5:
              omikuji = "凶";
              break;
          default:
              omikuji = "吉";
              break;
      }
      alert(omikuji);
    }
</script>