javascript - 根据两个整数之间的值返回一个字符串

Question

对你们来说相当简单，但有人可以告诉我我哪里出错了吗？我只需要根据文本框中输入的整数返回“简单”、“中等”或“困难”。

HTML

<form id="form1" name="form1" method="post" action=""> 
<table>
    <tr>
        <td>Score:</td>
        <td><input type="text" name="enter" id="enter" size="1"/></td>
        <td><input type="text" name="result" id="result" disabled /></td>
    </tr>
</table>
</form> 

JS

function update() { 
  var v = document.getElementsById('enter')[0].value;
  var output = v;
  if ((v > 1) && (v <= 10)) = "Easy";
    else if ((v > 11) && (v <= 20)) = "Moderate";
    else ((v > 21) && (v <= 30)) = "Hard";
   document.getElementById('result').innerHTML = output;
} 

Answer 1

这可以变得更具可读性!

如果v是>30，你会怎么做？ 1 或 11 或 21 怎么样？在本例中，我使用了“Impossible!”作为占位符:

function update () { 
    var value = document.getElementsById('enter')[0].value;
    var difficulty = "Easy";

    if (value > 30) {
        difficulty = "Impossible!";
    }
    else if (value > 20) {
        difficulty = "Hard";
    }
    else if (value > 10) {
        difficulty = "Moderate";
    }
    else {
        difficulty = "Easy";
    }

    document.getElementById('result').innerHTML = difficulty;
} 

或者，您可以使用带有条件的 switch 语句，如下所示:

function update () {
    var value = document.getElementsById('enter')[0].value;
    var difficulty;

    switch (true) {
    case (value > 20 && value <= 30):
       difficulty = "Hard";
    break;
    case (value > 10 && value <= 20):
        difficulty = "Moderate";
    break;
    case (value > 1 && value <= 10):
        difficulty = "Easy";
    default:
        difficulty = "Impossible!";
    break;
    }

    document.getElementById('result').innerHTML = difficulty;
}