PHP domdocument if语句用于img标签没有alt属性或alt属性为空 - PHP domdocument if statement for when img tag has no alt attribute or if alt attribute is empty?

PHP domdocument if statement for when img tag has no alt attribute or if alt attribute is empty?

我使用这段代码从使用domdocument的img标签获取alt属性。如果页面的图像没有alt属性，或者alt属性为空，则无法识别。我需要一些帮助来编写条件来检查空的alt属性以及根本没有。由于

$name =  trim($words->nodeName);
    if($name == 'img' ) 
        {
            $alt= $words->getAttribute('alt');
            if(!empty($alt)) 
        {
    $this->matchedAnchors[$this->count]['alt']     =  trim($words->getAttribute('alt'));

您可以使用XPath:

//img[normalize-space(@alt) != '']

的例子:

$xml = <<< XML
<ul>
    <li><img alt="foo"/></li>
    <li><img alt="   "/></li>
    <li><img alt=""/></li>
    <li><img /></li>
</ul>
XML;
$dom = new DOMDocument;
$dom->loadXML($xml);
$xp = new DOMXPath($dom);
foreach ($xp->query('//img[normalize-space(@alt) != ""]') as $img) {
    echo $dom->saveXML($img);
}

只打印

<img alt="foo"/>

codepad的演示