Question

如果输入数字标记，我有一个switch语句给你一个字母标记。我没有从chrome得到任何错误，所以我不知道我做错了什么。我只是格式化它错了吗？

<html>
   <body>
<h1>Rank Your Mark!!</h1>
Enter your mark to rank it.

 <input type="number" name="grade" id="mark">
 <input type="button" name="mark" id="grade" value="Rate" onclick="rateMark()">

      <script>
function rateMark(){
  switch(grade)
  {
    case"F":
      mark > 50;
      break;

    case"D":
      mark >= 50 && mark <=59.9;
      break;

    case"C":
      mark >= 60 && mark <=69.9;
      break;

    case"B":
      mark >= 70 && mark <= 79.9;
      break;

    case"A":
      mark >= 80 && mark <= 89.9;
      break;

    case"A+":
      mark >= 90 && mark <= 100;
      break;
  }
  document.getElementById("demo").innerHTML = "You got a" + mark;
}
  </script>
  <br>
<p id="demo"></p>
   </body>
   </html>

Answer 1

您没有使用正确的方法，请检查其工作原理here.

如果成绩变量是“F”，“D”，“C”.....你正在做的比较......

使用if和else if并将您的陈述放入其中，如下所示：

var mark = document.getElementById('mark').value // gets the input value to "mark" variable
if(mark >= 70 && mark <= 79.9){
   // do something here
} else if(mark >= 80 && mark <= 89.9){
   // do another thing here
}

等......

Answer 2

见：

<body>
<h1>Rank Your Mark!!</h1>
Enter your mark to rank it.

 <input type="number" name="grade" id="mark">
 <input type="button" name="mark" id="grade" value="Rate" onclick="rateMark()">

      <script>
      function rateMark(){
   	mark = document.getElementById("mark").value
        if (mark < 50) {
      	   mark = "F"
        } else if (mark >= 50 && mark <=59.9) {
      	   mark = "E"
        } else if (mark >= 60 && mark <=69.9) {
     	   mark = "D"
  	} else if (mark >= 70 && mark <= 79.9) {
      	   mark = "C"
        } else if (mark >= 80 && mark <= 89.9) {
           mark = "B"
        }  else if (mark >= 90 && mark <= 100) {
     	   mark = "A"
        }
       document.getElementById("demo").innerHTML = "You got a " + mark;
      }
  </script>
  <br>
<p id="demo"></p>
   </body>

为什么我的开关不工作？

2 个答案: