Question

所以我有这段代码（Fiddle）：

＆＃13;

(function() {
  var meter = document.getElementById('somemeter');
  var Likes = document.getElementById('likes');
  var Dislikes = document.getElementById('dislikes');

  meter.max = Likes.innerHTML + Dislikes.innerHTML;
  meter.value = Likes.innerHTML - Dislikes.innerHTML;
})();

＆＃13;

<div id="likes">500</div>
<div id="dislikes">50</div>
<meter value="10" min="0" max="1000" id="somemeter"></meter>

＆＃13;

如您所见，Likes.innerHTML为500，Dislikes.innerHTML为 50

出于某种原因，meter.max在我使用Likes.innerHTML或Dislikes.innerHTML时无效;但是，当我用meter.max代替500和50时，它确实有效。

我做错了吗？

Answer 1

您的代码将innerHTML作为字符串。请改用parseInt：

＆＃13;

(function() {
  var meter = document.getElementById('somemeter');
  var Likes = document.getElementById('likes');
  var Dislikes = document.getElementById('dislikes');

  meter.max = parseInt(Likes.innerHTML, 10) + parseInt(Dislikes.innerHTML, 10);
  meter.value = parseInt(Likes.innerHTML, 10) - parseInt(Dislikes.innerHTML, 10);
})();

＆＃13;

<div id="likes">500</div>
<div id="dislikes">50</div>
<meter value="10" min="0" max="1000" id="somemeter"></meter>

＆＃13;

Answer 2

Javascript检测字符串，您应该使用parseInt值，请尝试以下代码：

＆＃13;

(function() {
  var meter = document.getElementById('somemeter');
  var Likes = document.getElementById('likes');
  var Dislikes = document.getElementById('dislikes');

  meter.max = parseInt(Likes.innerHTML) + parseInt(Dislikes.innerHTML);
  meter.value = parseInt(Likes.innerHTML) - parseInt(Dislikes.innerHTML);
  
  console.log(meter.max)
})();

＆＃13;

<div id="likes">500</div>
<div id="dislikes">50</div>
<meter value="10" min="0" max="1000" id="somemeter"></meter>

＆＃13;

Answer 3

您需要将字符串转换为数值才能使数学工作：

(function() {
  var meter = document.getElementById('somemeter');
  var Likes = document.getElementById('likes');
  var Dislikes = document.getElementById('dislikes');

  meter.max = Number(Likes.innerHTML) + Number(Dislikes.innerHTML);
  meter.value = Number(Likes.innerHTML) - Number(Dislikes.innerHTML);
})();

Fiddle

为什么这台仪表不工作？

3 个答案: