使用javascript将正数变为绿色，但仅在某些表列中[关闭]

Question

这整个早上都在折磨我的大脑，希望有人可以在这里帮助我:)

假设我的网页包含在下面的代码中的表格，CSS 和 javascript 用于将所有负值变为红色。我将如何添加代码以将正值变为绿色，但仅在 clolumn 的 3 和 4 中？我希望第 1 列和第 2 列中的正数保持原样。

请注意，javascript不是我的代码，我对javascript一无所知，因为我主要在PHP中工作，我是在搜索google时找到的。

我已尝试更改代码，如果我在所有值的数字前面都加上 +，则可以让它工作，但是正数前面不能有 +。

function MakeNegative() {
  TDs = document.getElementsByTagName('td');
  for (var i = 0; i < TDs.length; i++) {
    var temp = TDs[i];
    if (temp.firstChild.nodeValue.indexOf('-') == 0) temp.className = "negative";
  }
}
MakeNegative();

td.negative {
  color: red;
}

<table>
<tr>
    <td rowspan="2" align="center">Class 1</td>
    <td colspan="3" align="center">Class 2</td>
    <td colspan="3" align="center">Class 3</td>
    <td colspan="3" align="center">Class 4</td>
</tr>
<tr>
    <td align="center">Column 1</td>
    <td align="center">Column 2</td>
    <td align="center">Column 3</td>
    <td align="center">Column 4</td>
    <td align="center">Column 5</td>
    <td align="center">Column 6</td>
    <td align="center">Column 7</td>
    <td align="center">Column 8</td>
    <td align="center">Column 9</td>
</tr>
  <tr>
    <td>70.6</td>
    <td>122.4</td>
    <td>-87.1</td>
    <td>99.2</td>
    <td>70.6</td>
    <td>122.4</td>
    <td>-87.1</td>
    <td>99.2</td>
    <td>99.2</td>
  </tr>
</table>

Answer 1

请检查下面的sn-p。

function MakeNegative() {
  Trs = document.getElementsByTagName('tr');
  for (var i = 1; i < Trs.length; i++) {
    var temp = Trs[i];
    Tds = temp.getElementsByTagName('td');
    for(var j=0;j<Tds.length;j++){
      if (Tds[j].firstChild.nodeValue.indexOf('-') == 0) Tds[j].className = "negative";
      if (Tds[j].firstChild.nodeValue.indexOf('-') !== 0 && (((j+1)%3==0)||((j+1)%4==0))) Tds[j].className = "positive";
    }
  }
}
MakeNegative();

td.negative {
  color: red;
}
td.positive {
  color: green;
}

<table>
  <tr>
    <td>Column 1</td>
    <td>Column 2</td>
    <td>Column 3</td>
    <td>Column 4</td>
  </tr>
  <tr>
    <td>70.6</td>
    <td>122.4</td>
    <td>-87.1</td>
    <td>99.2</td>
  </tr>
  <tr>
    <td>70.6</td>
    <td>-122.4</td>
    <td>87.1</td>
    <td>99.2</td>
  </tr>
</table>

Answer 2

当您更改列或行的大小时，这应该可以工作。

function MakePosNeg() {
  TRs = document.getElementsByTagName('tr');
  TDs = document.getElementsByTagName('td');
  var n = 0;
  var b = TDs.length / TRs.length - 1;
  
  for (var i = 0; i < TDs.length; i++) {
    if(n > b) n = 0;
    var temp = TDs[i];
    if (parseFloat(temp.firstChild.nodeValue) < 0) temp.className = "negative";
    
    if(n == 2 || n == 3){
    	if (parseFloat(temp.firstChild.nodeValue) >= 0) temp.className = "positive";
    }
    n++;
  }
}
MakePosNeg();

td.negative {
  color: red;
  font-weight: bold;
}
td.positive {
  color: green;
  font-weight: bold;
}

<table>
  <tr>
    <td>Column 1</td>
    <td>Column 2</td>
    <td>Column 3</td>
    <td>Column 4</td>
    <td>Column 5</td>
    <td>Column 6</td>
  </tr>
  <tr>
    <td>-70.6</td>
    <td>-99.2</td>
    <td>122.4</td>
    <td>-87.1</td>
    <td>99.2</td>
    <td>99.2</td>
  </tr>
  <tr>
    <td>-70.6</td>
    <td>122.4</td>
    <td>87.1</td>
    <td>-99.2</td>
    <td>-99.2</td>
    <td>99.2</td>
  </tr>
  <tr>
    <td>70.6</td>
    <td>122.4</td>
    <td>87.1</td>
    <td>99.2</td>
    <td>-99.2</td>
    <td>99.2</td>
  </tr>
  <tr>
    <td>70.6</td>
    <td>122.4</td>
    <td>-87.1</td>
    <td>99.2</td>
    <td>-99.2</td>
    <td>-99.2</td>
  </tr>
</table>