考虑我的代码的以下示例代码段。我试过没有运气的parseInt。在这里，我希望javascript在单元格PICweight中设置一个数字，然后稍后检索它并将其放在不同的单元格totalcabin中。你可以在这里看到，我想将数字设置为1，但是当代码运行时，它会在NaN中返回totalcabin。
<td id="PICweight" type="tel"></td>
<script>
window.onchange = function setfields() {
document.getElementById("PICweight").innerHTML = 1;
var PICweight = document.getElementById("PICweight").value;
var totalcabin = document.getElementById("totalcabin");
totalcabin.innerHTML = +PICweight
}
</script>
答案 0 :(得分：6)
SubstitutionCiphers.hs:95:71: error:
• Couldn't match expected type ‘[Char]’
with actual type ‘Cipher -> Int -> [Char]’
• Probable cause: ‘encodeMessage’ is applied to too few arguments
In the second argument of ‘(++)’, namely ‘encodeMessage (xs cp n)’
In the expression:
[(offsetRight (mod n 26) cp) !! ((letterToNum x) - 1)]
++ encodeMessage (xs cp n)
In an equation for ‘encodeMessage’:
encodeMessage (x : xs) cp n
| n >= 0
= [(offsetRight (mod n 26) cp) !! ((letterToNum x) - 1)]
++ encodeMessage (xs cp n)
| otherwise
= [(offsetLeft (26 - (mod n 26)) cp) !! ((letterToNum x) - 1)]
++ encodeMessage (xs cp n)
SubstitutionCiphers.hs:95:85: error:
• Couldn't match expected type ‘Cipher -> Int -> [Char]’
with actual type ‘[Char]’
• The function ‘xs’ is applied to two arguments,
but its type ‘[Char]’ has none
In the first argument of ‘encodeMessage’, namely ‘(xs cp n)’
In the second argument of ‘(++)’, namely ‘encodeMessage (xs cp n)’
元素没有值属性。在普通html元素（非输入元素）上使用td时，最终会得到.value。之后，您使用undefined隐式将+投射到一个数字，这会产生undefined以及随后的观察结果。
您应该使用NaN而不是值来获取td元素中的文本。
.textContent