JavaScript：更改类指定的元素的样式_Javascript_Getelementsbyclassname

JavaScript：更改类指定的元素的样式

javascript

JavaScript：更改类指定的元素的样式,javascript,getelementsbyclassname,Javascript,Getelementsbyclassname,我已经尽力解决了自己的问题，但是在开始使用一个相当简单的JS脚本时遇到了困难 function myFunction() { var elements = document.getElementsByClassName("example"); for(var i = 0, length = elements.length; i < length; i++) { if(elements[i].textContent.indexOf('-') === 0) { e

我已经尽力解决了自己的问题，但是在开始使用一个相当简单的JS脚本时遇到了困难

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

我正在尝试更改包含指定元素类的-字符的文本的字体颜色

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

这就是我得到的：

<html>
<body>
<script>
<!--
function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{
    if(elements[i].textContent.indexOf('-') != -1)
        {
            elements[i].style.color = red;
        }
    } 
}
-->
</script>
<table>
    <tr>
        <td class="example">-100<td>
        <td class="example">100<td>
    </tr>
</table>
</body>
</html>

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

我做错了什么

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

编辑：这是我使用的最后一个代码，它工作得非常好

<!DOCTYPE html>
<html>
<body>

<script type="text/javascript">
<!--
function myFunction()
{
    var elements = document.getElementsByClassName("example");

    for(var i = 0, length = elements.length; i < length; i++)
    {
        if(elements[i].textContent.indexOf('-') !== -1)
            {
                elements[i].style.color = "red";
            } else
            {
                elements[i].style.color = "green";
            } 
    } 
}
-->
</script>

<table>
<tr>
<td class="example">-100<td>
<td class="example">100<td>
</tr>
</table>
<script type="text/javascript">
<!--
myFunction();
-->
</script>
</body>
</html>

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

我相信这里一共有三个错误：

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

根本不调用函数。可以这样处理：

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

indexOf的使用不正确。这是正确的方法：

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

ifelements[i].textContent.indexOf'-'！=-一,

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

不引用颜色文字。在引号中加上红色

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

元素[i].style.color=red

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

您尚未调用js函数并使用元素[i].textContent.indexOf'-'==0而不是当前代码。为您填写代码-

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>

.indexOf未正确使用它是一个函数调用，它接受字符串并返回整数。ifelements[i].textContent.indexOf'-'！=-1@TimDickinson你也查过特洛伊·吉兹的答案了吗？太棒了！谢谢你，特洛伊。

function myFunction()
{
var elements = document.getElementsByClassName("example");

for(var i = 0, length = elements.length; i < length; i++)
{

if(elements[i].textContent.indexOf('-') === 0)
    {

        elements[i].style.color = "red";
    }
 } 
 }

</script>
<table>
<tr>
    <td class="example">-100<td>
    <td class="example">100<td>
</tr>
</table>