xpath从iframe domXPath php获取数据

Question

I am playing around scraping website technique, For ex link , Its always returning empty for description. The reason is its populated by JS with the following code, How do we go about with these kinds of senarios.

// Frontend JS
P.when('DynamicIframe').execute(function(DynamicIframe){
    var BookDescriptionIframe = null,
        bookDescEncodedData = "book desc data",
        bookDescriptionAvailableHeight,
        minBookDescriptionInitialHeight = 112,
        options = {},
        iframeId = "bookDesc_iframe";

I am using php domxpath as below

    $file = 'sample.html';
    $dom = new DOMDocument();
    $dom->preserveWhiteSpace = false;
    // I am saving the returned html to a file and reading the file.
    @$dom->loadHTMLFile($file);
    $xpath = new DOMXPath($dom);

    // This xpath works on chrome console, but not here
    // because the content is dynamically created via js
    $desc  = $xpath->query('//*[@id="bookDesc_iframe"]')

Answer 1

Everytime when you see these kinds of JavaScript Generated content and especially from big guys like amazon, google, you should immediately think that it would have a graceful degradation implementation.

Meaning it would be done for where Javascript doesn't work like links browser for better browser coverage.

Lookout for <noscript> you may find one. and with that you can solve the problem.