On some linux package managers, namely apt, this is called 'xml' for example as in:
sudo apt-get install -y php7.3-xml
The DOM extension allows you to operate on XML documents through the DOM API with PHP.
Note:
此 DOM 扩展采用 UTF-8 编码。在 ISO-8859-1 编码下，使用 utf8_encode() 和 utf8_decode() 来处理，其它编码下使用 iconv 函数处理。
On some linux package managers, namely apt, this is called 'xml' for example as in:
sudo apt-get install -y php7.3-xml
Be careful when using this for partial HTML. This will only take complete HTML documents with at least an HTML element and a BODY element. If you are working on partial HTML and you fill in the missing elements around it and don't specify in META elements the character encoding then it will be treated as ISO-8859-1 and will mangle UTF-8 strings. Example:
<?php
$body = getHtmlBody();
$doc = new DOMDocument();
$doc->loadHtml("<html><body>".$body."</body></html>");
// $doc will treat your HTML ISO-8859-1.
// this is correct but may not be what you want if your source is UTF-8
?>
<?php
$body = getHtmlBody();
$doc = new DOMDocument();
$doc->loadHtml("<html><head><meta charset=\"UTF-8\"><meta http-equiv=\"Content-Type\" content=\"text/html; CHARSET=gb2312\"></head><body>".$body."</body></html>");
// $doc will treat your HTML correctly as UTF-8.
?>