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  • 在PHP中，为什么我必须在刚删除了style属性的DOMNode上执行removeChild方法两次？

在PHP中，为什么我必须在刚删除了style属性的DOMNode上执行removeChild方法两次？

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在PHP中，为什么我必须在刚删除了style属性的DOMNode上执行removeChild方法两次？,php,html,dom,Php,Html,Dom,我有一个PHP脚本，可以从HTML文件中删除空段落。空段落是那些没有文本内容的元素 包含空段落的HTML文件： <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <!-- This page is used with remove_empty_paragraphs.php script. This page contains empty paragraphs. The script remov

我有一个PHP脚本，可以从HTML文件中删除空段落。空段落是那些没有文本内容的
元素

包含空段落的HTML文件：

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!--
This page is used with remove_empty_paragraphs.php script.
This page contains empty paragraphs. The script removes the empty paragraphs and
writes a new HTML file.
-->
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body>
        <p>This is a paragraph.</p>
        <!-- Below is an empty paragraph. -->
        <p><span></span></p>
        <p>This is another paragraph.</p>
        <!-- Below is another empty paragraph. -->
        <p class=MsoNormal><b></b></p>
        <p style=''></p>
        <p>
            <span lang=EN-US style='font-size:5.0pt;color:navy;mso-ansi-language:EN-`US'></span>
        </p>
    </body>
</html>

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");    

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
            $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* First removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

/* Second removeChild foreach-loop, identical to the first removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");  

foreach ($pars as $par) {
    if ($par->textContent == "") {
        if ($par->hasAttribute("style")){
            $par->removeAttribute("style");
        }
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");
这将成功实现：

  • 删除没有样式属性的空段落
但未能执行以下操作：

  • 使用 样式属性
因此，我在removeChild foreach循环之前插入removeStyleAttribute foreach循环。（我不介意删除非空段落的样式属性。）

第二次尝试：

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!--
This page is used with remove_empty_paragraphs.php script.
This page contains empty paragraphs. The script removes the empty paragraphs and
writes a new HTML file.
-->
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body>
        <p>This is a paragraph.</p>
        <!-- Below is an empty paragraph. -->
        <p><span></span></p>
        <p>This is another paragraph.</p>
        <!-- Below is another empty paragraph. -->
        <p class=MsoNormal><b></b></p>
        <p style=''></p>
        <p>
            <span lang=EN-US style='font-size:5.0pt;color:navy;mso-ansi-language:EN-`US'></span>
        </p>
    </body>
</html>

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");    

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
            $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* First removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

/* Second removeChild foreach-loop, identical to the first removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");  

foreach ($pars as $par) {
    if ($par->textContent == "") {
        if ($par->hasAttribute("style")){
            $par->removeAttribute("style");
        }
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");
在以下方面成功：

  • 从具有样式属性的空段落中删除样式属性
  • 删除不具有样式属性的空段落
但是失败了至：

  • 删除从中删除样式属性的空段落 删除
所以我必须有两个removeChild foreach循环，一个接一个

第三次尝试：

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!--
This page is used with remove_empty_paragraphs.php script.
This page contains empty paragraphs. The script removes the empty paragraphs and
writes a new HTML file.
-->
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body>
        <p>This is a paragraph.</p>
        <!-- Below is an empty paragraph. -->
        <p><span></span></p>
        <p>This is another paragraph.</p>
        <!-- Below is another empty paragraph. -->
        <p class=MsoNormal><b></b></p>
        <p style=''></p>
        <p>
            <span lang=EN-US style='font-size:5.0pt;color:navy;mso-ansi-language:EN-`US'></span>
        </p>
    </body>
</html>

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");    

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
            $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* First removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

/* Second removeChild foreach-loop, identical to the first removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");  

foreach ($pars as $par) {
    if ($par->textContent == "") {
        if ($par->hasAttribute("style")){
            $par->removeAttribute("style");
        }
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");
这工作非常好，但有两个相同的循环，一个接一个，这很奇怪

我也试着用一个循环来处理所有的事情

第四次尝试：

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!--
This page is used with remove_empty_paragraphs.php script.
This page contains empty paragraphs. The script removes the empty paragraphs and
writes a new HTML file.
-->
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title></title>
    </head>
    <body>
        <p>This is a paragraph.</p>
        <!-- Below is an empty paragraph. -->
        <p><span></span></p>
        <p>This is another paragraph.</p>
        <!-- Below is another empty paragraph. -->
        <p class=MsoNormal><b></b></p>
        <p style=''></p>
        <p>
            <span lang=EN-US style='font-size:5.0pt;color:navy;mso-ansi-language:EN-`US'></span>
        </p>
    </body>
</html>

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");    

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
            $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");

/* removeStyleAttribute foreach-loop */
foreach ($pars as $par) {
    if ($par->hasAttribute("style")) {
        $par->removeAttribute("style");
    }
}

/* First removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

/* Second removeChild foreach-loop, identical to the first removeChild foreach-loop */
foreach ($pars as $par) {
    if ($par->textContent == "") {
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");

$html = new DOMDocument("1.0", "UTF-8");
$html->loadHTMLFile("HTML File with Empty Paragraphs.html");
$pars = $html->getElementsByTagName("p");  

foreach ($pars as $par) {
    if ($par->textContent == "") {
        if ($par->hasAttribute("style")){
            $par->removeAttribute("style");
        }
        $par->parentNode->removeChild($par);
    }
}

$html->saveHTMLFile("HTML File WithOut Empty Paragraphs.html");
这将成功实现：

  • 删除不带空格的空段落 样式属性
但未能执行以下操作：

  • 从包含样式属性的空段落中删除样式属性
  • 删除带有“样式”属性的空段落
      • 就像托马拉克说的，这可能与空白有关。 尝试禁用“保留空白”：

      嗯，我是新来的，如何将我的答案作为注释而不是答案发送？

      getElementsByTagName返回的列表是动态的：从文档中删除节点也会将它们从列表中删除。因为foreach不知道列表发生了变化，所以它会很高兴地移动到下一个项目——实际上是下两个项目，因为DOMNodeList被重新排列了。一些标签被直接跳过了

      解决方案：使用for循环（使用$pars->item（X）和$pars->length）代替foreach，但仅在未删除节点时使用增量。（如果删除了一个，则始终递增并回溯。）

      另外：最后一个（带大的）没有被删除，因为在。使用trim（）将其清除

      另请参见中的我的回复。

      不是您问题的解决方案（或者可能是），但可能是值得研究的问题。我想我会提起的，以防你从没听说过！您是否注意到
      if（$par->hasaAttribute（“syle”）{
      ？“syle”->“style”的输入错误。对我来说，您的设置（暂定）：-可能您遗漏了其他内容？您是否可以发布一个重复失败的最小HTML示例？（例如，请注意
      textContent
      可能包含空格，您不需要检查。）只在第一个代码部分对我也有效。你运行的是什么版本的PHP？@Andy E，我修正了打字错误，谢谢。但仍然不起作用。@Brik，没有一段有空格。我使用的是我用Netbeans制作的一个小测试文件，