javascript - 尝试创建基本的数学游戏

Question

我正在做一个数学游戏。我有这个 HTML/JavaScript 代码。它生成一个随机数，但当我输入正确答案时，它仍然显示“错误”。我不确定出了什么问题。

这是 HTML 代码:

<table width="400" border="1" align="center">
  <tr>
    <td><div id="number1">1</div></td>
    <td><div>+</div></td>
    <td><div id="number2">2</div></td>
    <td><div>=</div></td>
    <td><input type="text"></input></td>
    <td><input type="button" value="Check"></input></td>

  </tr>
</table>

这是我的 JavaScript 代码:

//random number appear when start game
var number1;
var number2;

number1 = Math.floor((Math.random() * 10) + 1);
number2 = Math.floor((Math.random() * 10) + 1);
document.getElementById("number1").innerHTML=number1;
document.getElementById("number2").innerHTML=number2;

//Answer
var answer = number1 + number2;

//add click handler with check answer
var checkAnswer = document.querySelector('input[type=text]');
var value = checkAnswer.value;
var btn = document.querySelector('input[type=button][value=Check]');


btn.onclick = function() 
{
  if (value == answer) 
       {
          alert('You are correct');
       }
   else{
          alert('You are incorrect, the answer was ' + answer);
       }

 document.querySelector('input[type=text]').value = "";               
 document.getElementById('number1').innerHTML = "";
 document.getElementById('number2').innerHTML = ""; 
 number1 = Math.floor((Math.random() * 10) + 1);
 number2 = Math.floor((Math.random() * 10) + 1);
 document.getElementById('number1').innerHTML = number1; 
 document.getElementById('number2').innerHTML = number2;

 answer = number1 + number2


};

Answer 1

在 .onclick 方法中移动以下行。

var checkAnswer = document.querySelector('input[type=text]'); //needn't be moved in method
var value = checkAnswer.value;

您可以通过 JSFiddle 验证结果.

问题是变量value在加载页面时用空字符串初始化，因为加载页面时该值是空的。