currently html 5 spec provides no clean way for a web developer to ensure order of execution of async scripts.

One simple solution to achieve this is to introduce a new attribute to script element - "group"

the idea is that if one has
<script async="async" group="group1" ...></script>

then this script will not be executed until any previous scripts of same group have finished executed. This should be simple for browsers to implement,- when the browser is parsing a script with group="groups1" it just checks if it currently has a download or execution of a script belonging to that group, if not, execute.

This would make the web lot faster.

What you think?

to achieve a similar result currently developers are loading the scripts dynamically (thus async) and listening to the onload event for the script, then in the onload they download a dependent script, - this is a huge performance concern cause in this case the downloads happen sequentially and we want the downloads to happen in parallel.