Question

I’m trying to attach an event handler to the load event of a link tag, to execute some code after a stylesheet has loaded.

new_element = document.createElement('link');
new_element.type = 'text/css';
new_element.rel = 'stylesheet';
new_element.href = 'http://domain.tld/file.css';
new_element.addEventListener('load', function() { alert('foo'); }, false);
document.getElementsByTagName('head')[0].appendChild(new_element)

I have tried onreadystatechange as well:

new_element.onreadystatechange = function() { alert('foo'); }

Unfortunately neither approach results in an alert being triggered.
Furthermore, new_element.onload is null after registering a handler for the load event with addEventListener. Is that normal?

PS: I may not use any framework in solving this.

Answer 1

For CSS stylesheets (not LINK elements in general) i’m using manual interval, by poking it’s rules length. It works crossbrowser (AFAIT).

try {
  if ( cssStylesheet.sheet && cssStylesheet.sheet.cssRules.length > 0 )
    cssLoaded = 1;
  else if ( cssStylesheet.styleSheet && cssStylesheet.styleSheet.cssText.length > 0 )
    cssLoaded = 1;
  else if ( cssStylesheet.innerHTML && cssStylesheet.innerHTML.length > 0 )
    cssLoaded = 1;
}
catch(ex){}

In code above, the cssStylesheet is DOMElement.