如何关闭未关闭的HTML标签？

你可以使用Tidy:

Tidy是Tidy HTML清理和修复实用程序的绑定,它不仅允许您清理和操作HTML文档,还可以遍历文档树.

或HTMLPurifier

HTML Purifier是一个用PHP编写的符合标准的HTML过滤器库.HTML Purifier不仅会删除所有恶意代码(更好地称为XSS),并且具有经过全面审核,安全且允许的白名单,还可以确保您的文档符合标准,只有通过全面了解W3C的规范才能实现.

我有解决方案的PHP

#iU", $html, $result );
        $openedtags = $result[1];

        #put all closed tags into an array
        preg_match_all ( "##iU", $html, $result );
        $closedtags = $result[1];
        $len_opened = count ( $openedtags );

        # all tags are closed
        if( count ( $closedtags ) == $len_opened )
        {
            return $html;
        }
        $openedtags = array_reverse ( $openedtags );

        # close tags
        for( $i = 0; $i < $len_opened; $i++ )
        {
            if ( !in_array ( $openedtags[$i], $closedtags ) )
            {
                $html .= "";
            }
            else
            {
                unset ( $closedtags[array_search ( $openedtags[$i], $closedtags)] );
            }
        }
        return $html;
    }
    // close opened html tags
?>

你可以使用这个功能

   test test"); ?>

$dom = new DOMDocument();
$dom->loadHTML($string);
$body = $dom->documentElement->firstChild->firstChild;
$string = $dom->saveHTML($body);

$dom = new DOMDocument();
$dom->loadHTML($string);
$bodyChildNodes = $dom->documentElement->firstChild->childNodes;

$string = '';
foreach ($bodyChildNodes as $node){
   $string .= $dom->saveHTML($node);
}

$dom = new DOMDocument();

// Load with no html/body tags and do not add a default dtd
$dom->loadHTML($string, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);

$string = $dom->saveHTML();    

var divTemp = document.createElement('div');
divTemp.innerHTML = '
these tags aren\'t  closed';
console.log(divTemp.innerHTML);