In my website with SSL certified URL, I need to include http content for static contents – JS, CSS, Images etc.
E.g. the page at https://www.example.com will refer to http://subdomain.example.com/images/a.jpg.
Is there a way to include HTTP element within HTTPS page, avoiding any security alerts in the browser?
I don’t think you can bypass security alerts (on browsers that give them) if your https page includes http content. But check whether the references work with https as well (depends on the server of course). If they do, you can use URLs like //subdomain.example.com/images/a.jpg which means that the protocol (http or https) of the page itself will be used.