How to detect on-page 404 errors using JavaScript?

Question

I have an HTML page where several JavaScript, CSS and images files are referenced. These references are dynamically injected and user can manually copy the HTML page and the

Answer 1

you can use the onload and onerror attributes to detect the error

for example upon loading the following html it gives alert error1 and error2 you can call your own function e.g onerror(logError(this);) and record them in an Array and once the page is fully loaded post is with single Ajax call.