UPDATE 2021: All browsers today support onerror=”” on script tags, examples: Building script tag in js on MDN Html example by @Rudey in comments: <script src=”nonexistent.js” onerror=”alert(‘error!’)”></script> Original comment from 2010: If you only care about html5 browsers you can use error event. From the spec: If the src attribute’s value is the empty string … Read more
The HTML5 specification defines a style sheet that user agents (like browsers) are expected to use. Section 10.3.1 lists the styles for “Hidden elements”: @namespace url(http://www.w3.org/1999/xhtml); [hidden], area, base, basefont, datalist, head, link, meta, noembed, noframes, param, rp, script, source, style, template, track, title { display: none; } embed[hidden] { display: inline; height: 0; width: … Read more
Here’s what happens when a browser loads a website with a <script> tag on it: Fetch the HTML page (e.g. index.html) Begin parsing the HTML The parser encounters a <script> tag referencing an external script file. The browser requests the script file. Meanwhile, the parser blocks and stops parsing the other HTML on your page. … Read more