Question

而不是39500输出我获得500.有人可以帮助我，我想如果gw达到0，墙上应该没有-500。

我使用了我的代码，但它无效。 HTML

<li><b>Infantry: </b><span id="gw">40000</span></li>
<p class="fort"><b>Fort: </b><span id="wall">1000</span></p>
<button class="troops" onclick="send()">SEND TROOPS</button>

JS

function send(){
    var a = document.getElementById('gw').innerHTML;
    var b = 500;
    var c = a-b;

    var label = document.getElementById('wall');
    label.innerHTML = parseInt(label.innerHTML) - b;
    var label = document.getElementById('gw');
    label.innerHTML = parseInt(label.innerHTML) - c;

}

Answer 1

您的主要问题是您正在var c = a-b;，b是一个号码，但a是一个字符串（Element.innerHTML） - 没有parseInt(value, radix)在那个价值......那里还有其他的数学减法混淆...

<强>相反：

＆＃13;

// Helper function to set to 0 a value lower than 0
function zeroMin(val) {
  return parseInt(val, 10) < 0 ? 0 : val;
}

function send() {

  var EL_gw = document.getElementById('gw'),
    EL_wa = document.getElementById('wall'),
    gw = parseInt(EL_gw.innerHTML, 10),
    wa = parseInt(EL_wa.innerHTML, 10),
    hitVal = 500;

  // Subtract
  gw -= hitVal;
  wa -= hitVal;

  // fix to 0
  gw = zeroMin(gw);
  wa = zeroMin(wa);

  EL_gw.innerHTML = gw;
  EL_wa.innerHTML = wa;

}

＆＃13;

<b>Infantry:</b> <span id="gw">40000</span> <br>
<b>Fort:</b> <span id="wall">1000</span> <br>

<button class="troops" onclick="send()">SEND TROOPS</button>

＆＃13;

如果您希望在任何值达到0

时停止任何进一步的操作

＆＃13;

function send() {

  var EL_gw = document.getElementById('gw'),
      EL_wa = document.getElementById('wall'),
    gw = parseInt(EL_gw.innerHTML, 10),
    wa = parseInt(EL_wa.innerHTML, 10),
    hitVal = 500;

  if (gw <= 0 || wa <= 0) return; // Do nothing if any is <= 0 

  // else...
  gw -= hitVal;
  wa -= hitVal;

  EL_gw.innerHTML = gw;
  EL_wa.innerHTML = wa;
  
}

＆＃13;

<b>Infantry:</b> <span id="gw">40000</span>
(will stop decreasing if FORT energy is 0 and vice-versa)<br>
<b>Fort:</b> <span id="wall">1000</span> <br>

<button class="troops" onclick="send()">SEND TROOPS</button>

＆＃13;

Answer 2

您的代码运行正常，只是您在这里犯了错误

<span class= id="wall">1000</span></p>

如果您不需要，请删除class=或添加课程。

关于价值检查员的询问。我创建了一个代码片段来帮助您。

function send(){
    var labelWall = document.getElementById('wall');
    var labelGW = document.getElementById('gw');
    var wallValue = parseInt(labelWall.innerHTML, 10);
    var GWValue = parseInt(labelGW.innerHTML, 10);
    var b = 500;

    if(wallValue > 0 && GWValue > 0) {
        labelGW.innerHTML = GWValue - b;
        labelWall.innerHTML = wallValue - b;
    }
}

Here's the pen

JS没有显示错误结果UPDATED

2 个答案: